Mineralogy

A little bit more minerals, not lees amazing!

2012-01-20T17:36:00.000-06:00

Sapphire, pyrrhotite, wulfenite, pyromorphite, aquamarine, zircon, calcite, morganite, polibasyte and proustite, tourmaline, fluorite, scheelite! simply awsome!

2011-11-20T19:41:00.001-06:00

Topaz, Scheelite, Fluorite, Pyrrhotite, Copper, Silver, Millerite from Spain to Pakistan, Russia, Mexico and Michigan! to take your breath away!

2011-09-03T10:50:00.001-05:00

From top to bottom:
Topaz in Calcite matrix - From Katlang, Mardan District, Northwest Frontier Province, Pakistan. Scheelite set with Quartz on matrix - From the Gharmung Area, Skardu District, Baltistan, Northern Areas of Pakistan.
Fluorite with blades of white Barite - From Berbes, Berbes Mining Area, Ribadesella, Asturias, Spain.
Acanthite and curling Native Silver wires - From the Reyes Mine in Guanajuato, Mexico.
Pyrrhotites on Quartz crystals - From the Nikolaevskiy Mine, Dal'negorsk, Primorskiy Kray, Russia.
Native Copper - From the Calumet & Hecla Mine, Calumet, Houghton County, Michigan.
Botryoidal Chalcedony and fine Millerite crystals - From Halls Gap, Lincoln County, Kentucky.
Red Beryl crystals in and atop Rhyolite matrix - From the Wah Wah Mountains near Delta, Utah.
Boleite with Calcite on hand matrix - From Boleo, Baja California, Mexico.

Bloody minerals shouldn't be a bad word in UK, some as this red!

2011-06-30T22:01:00.008-05:00

Legrandite and Adamite from the famous Ojuela Mine in Mapimi, Durango Mexico, and of quartz... many more

2011-06-04T21:15:00.018-05:00

Monoclinic prismatic Legrandite crystals with Limonite matrix From the Ojuela Mine in Mapimi, Durango, Mexico - Zn2(AsO4)(OH)•(H2O) - Named after the Belgian mining engineer, Legrande.

Trigonal hexagonal scalenohedral Rhodochrosite in cluster on Quartz crystals from the Hedgehog Pocket, Main Stope Drift, Sweet Home Mine, Alma, Colorado - MnCO3 - From the Greek rhodon -"rose" and chroma - "color."

Hexagonal dihexagonal dipyramidal Beryl var. Aquamarine crystal with tourmaline Schorl rom the Erongo Mine, Namibia, SW Africa - Be3Al2Si6O18 - From the ancient Greek, beryllos, signifying a "precious blue-green color of sea water" stone.

Orthorhombic dipyramidal Barite crystal on reddish Hematite & Dolomite covered matrix from Frizington, West Cumberland Iron Field, North and Western Region (Cumberland), Cumbria, England - BaSO4 - From the Greek, baryos, "heavy."

Trigonal ditrigonal pyramidal Pyrargyrite crystals on top of Calcite rhombs from the Samson Mine, St. Andreasberg, Harz, Germany - Ag3SbS3 - From the Samson Mine, St. Andreasberg, Harz, Germany. From the Greek, pyr and argyros, "fire-silver" in allusion to color and silver content.

Orthorhombic dipyramidal Forsterite var. Peridot on Magnetite from Sapat Gali, Naran-Kagan Valley, Kohistan District, North-West Frontier Province, Pakistan - Mg2(SiO4) -
Named for Johann Forster, German naturalist.

Orthorhombic dipyramidal Adamite clusters on Limonite from the Ojuela Mine, Mapimí, Durango, Mexico - Zn2(AsO4)(OH) - Named after the French mineralogist Gilbert Joseph Adam (1795-1881).

Rhodochrosite, Calcite, Scheelite, Spessartine, Pyrrhotite, Millerite, and more all together in one post!

2011-05-19T18:06:00.008-05:00

In order of appearance from the top down:

Rhombs of Rhodochrosite atop Tetrahedrite and Quartz matrix! From the Sweet Home Mine, Alma, Park County, Colorado.
Measures 3.1 cm by 3 cm by 3.5 cm in total size.

Twinned Golden Calcite with Sphalerite on matrix! From the Denton Mine, Harris Creek District, Hardin County, Illinois.
Measures 7 cm by 7.2 cm by 5.2 cm in total size.

Scheelite crystal with glassy Adularia! From Mt Xuebaoding, Pingwu Co., Mianyang Prefecture, Sichuan Province of China. Measures 7.3 cm by 5.5 cm by 4.4 cm in total size.

Spessartine Garnet with dark botryoidal Goethite! From Tongbei, Yunxiao Co., Zhangzhou Prefecture, Fujian Province, China.
Measures 12.5 cm by 10.2 cm in size.

Large pyramidal Pyrrhotites on Quartz crystals! From the Nikolaevskiy Mine, Dal'negorsk, Primorskiy Kray, Russia.
Measures 7 cm by 12.6 cm by 10 cm in total size.

Cavern of botryoidal Chalcedony and fine Millerite crystals! From Halls Gap, Lincoln County, Kentucky.
Measures 7.2 cm by 11 cm by 6.8 cm in size.

Lustrous crystals of Pyrargyrite nestled between brown Calcite crystals and casts!From Level 630 of the San Guillermo Vein, San Luis Shaft, Fresnillo, Zacatecas, Mexico.
Measures 3 cm by 4.5 cm in size.

Combination of Barite and Gypsum crystals on Yellow Calcite! From the Elk Creek locality, Dalzell, Meade County, South Dakota.
Measures 7.5 cm by 15.3 cm by 12.5 cm in size.

Simply Amazing!

If you want to buy beautiful minerals, bring lots of money!

2011-05-14T12:36:00.012-05:00

A good challenge: Walk the aisles of the Tucson Gem and Mineral show, and mentally buy the ones you like! I confess, I spent millions in less than 100 yards wow! Here, in order of appearance: rhodochrosite, emerald, again rhodochrosite, native silver, kunzite, fluorite/barite acanthite, native copper and ruby red beryl. Impressive specimens that adorn the museums and private collections, like that of Rep. Romero de Tehuacan Puebla, a beautiful museum with amazing specimens such as legrandita, adamite, pyrites from Naica, etc. I used to take my students to this museum on an unforgettable journey of two days, after visiting the museum, Dr. Romero used to take us to a tour around his state of the art chicken farm. I lost track of my students, and obviously of the Mineral Museum of Tehuacan, unique in Mexico at least in the 80's, of course, the Deputy Romero died a few years ago.

In a recent visit I did to a gem & mineral show in Houston, I saw specimens worth almost $100,000 USD, I could not believe it. That inspired my title of this post. May 2011

Fluorite lego? No, actual crystals directly from Mother Nature

2011-03-27T13:35:00.008-05:00

From various locations, in its amazing variety of colors and habits, Fluorite is a fantastic mineral. Let me start from a location I visited for several months, such as Naica, Chihuahua in Northern Mexico whose location is off the "Panamerican Freeway" between Camargo and Delicias. From this mine, fluorite and other beautiful crystals have been collected, and it became world famous for its recently discovered giant gypsum crystals cave. Naica produced unique crystals of fluorite that vary from a very pale pink to almost transparent specimens with pyrite crystals inside, some of these in my private collection. I worked in this mine while I was still in College back in the late 70's, and to tell you the truth, I really enjoyed it, as I was assistant of the most prominent Mineralogist in Mexico Dr Raul Ortiz Asiain, and my passion for minerals was already there.

Also, pictures of fluorite from Pointe Kurz (3600 m altitude), Mont Blanc Massif, Haute-Savoie, France, and finally from Caldera 3, Mina Moscona, Solís, Corvera, Asturias Spain

Fluorite:

Chemical Formula: CaF2
Composition: Molecular Weight = 78.07 gm
Calcium 51.33 % Ca 71.83 % CaO
Fluorine 48.67 % F 48.67 % F
Environment: Low temperature vein deposits
Crystal System: Isometric - HexoctahedralH-M Symbol
Cleavage: {111} Perfect, {111} Perfect, {111} Perfect
Color: White, Yellow, Green, Red, Blue.
Density: 3.01 - 3.25, Average = 3.13
Diaphaneity: Transparent to subtranslucent
Fracture: Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern.
Habit: Crystalline - Coarse - Occurs as well-formed coarse sized crystals.
Habit: Disseminated - Occurs in small, distinct particles dispersed in matrix.
Habit: Massive - Granular - Common texture observed in granite and other igneous rock.
Hardness: 4 - Fluorite
Luminescence: Fluorescent, Short UV=blue, Long UV=blue.
Luster: Vitreous (Glassy)
Streak: White

Lead vanadate forms Vanadinite, discovered in Mexico

2010-09-01T21:33:00.002-05:00

Mine: San Carlos (Mina Apex), San Carlos, Manuel Benavides, Chihuahua Mexico
Pb5(VO4)3Cl

Vanadinite is an uncommon mineral, only occurring as the result of chemical alterations to a pre-existing material. It is therefore known as a secondary mineral. It is found in arid climates and forms by oxidation of primary lead minerals. Vanadinite is especially found in association with the lead sulfide, galena. Other associated minerals include wulfenite, limonite, and barite.[2][4][5]

It was originally discovered in Mexico by the Spanish mineralogist Andrés Manuel del Río in 1801. He called the mineral "brown lead" and asserted that it contained a new element, which he first named pancromium and later, erythronium. However, he was later led to believe that this was not a new element but merely an impure form of chromium. In 1830, Nils Gabriel Sefström discovered a new element, which he named vanadium. It was later revealed that this was identical to the metal discovered earlier by Andrés Manuel del Río. Del Río's "brown lead" was also rediscovered, in 1838 in Zimapan, Hidalgo, Mexico, and was named vanadinite due its high vanadium content. Other names that have since been given to vanadinite are johnstonite and lead vanadate.

Along with carnotite and roscoelite, vanadinite is one of the main industrial ores of the element vanadium, which can be extracted by roasting and smelting. It is occasionally used as a source of lead. A common process for extracting the vanadium begins with the heating of vanadinite with salt (NaCl) or sodium carbonate (Na2CO3) at about 850°C to produce sodium vanadate (NaVO3). This is dissolved in water and then treated with ammonium chloride to give an orange coloured precipitate of ammonium metavanadate. This is then melted to form a crude form of vanadium pentoxide (V2O5). Reduction of vanadium pentoxide with calcium gives pure vanadium.

Sources: WEikipedia and the University of life!

Featured blog

2010-05-03T08:50:00.001-05:00

Blog award

I am sad seeing these beauties in women's rings / collars!

2010-04-17T11:06:00.011-05:00

In order of appearance:

Tourmalines on Cleavelandite blades from the Himalaya Mine, Mesa Grande District, San Diego County, California

Linarite from the Grand Reef Mine in Graham County, Arizona

Prousite sitting atop a Polybasite cluster from the Uchucchacua Mine, Oyon Province, Lima Department, Peru.

Tourmaline from the 1974 Pocket, Tourmaline Queen Mine, San Diego County, California

Galena from the Tsumeb Mine in Tsumeb, Namibia, SW Africa.

Adamite from the Ojuela mine in Mapimi, Durango Mexico

For sure, these crystals ore from another galaxy!

2010-04-17T10:30:00.007-05:00

By order of appearance:

Beryl var. Emerald from a locality near Alabashka, Ural Mountains, Russia

Amazonite crystals with Smoky Quartz and Albite from Sentinel Rock, El Paso County, Colorado

Silver from Imiter Mine in Morocco

Scheelite with fluorite and muscovite from the Mt. Xuebaoding Mine, Pingwu, Sichuan Province of China

Red beryl from the Wah Wah Mountains near Delta, Utah

Mimetite from San Pedro Corralitos, Chihuahua Mexico

Spessartine garnets from Nani, Loliondo, Arusha Region, Tanzania

More jaw dropping specimens!

2010-01-24T12:43:00.009-06:00

Kunzite, Elbaite, Quartz and Albite
Cabinet
Nuristan
Laghman Prov., Afghanistan, Asia

Fluorite
Miniature
Dow Scar Vein, Hilton Mine
Scordale, Cumbria, England, Europe

Rhodochrosite
Small Miniature
Santa Eulalia
Chihuahua, Mexico

Neptunite
Small Cabinet
Benitoite Gem Mine
San Benito County, California

Wulfenite
Thumbnail
Los Lamentos
Chihuahua, Mexico

Specimens with a beauty beyond this planet!

2009-11-26T09:36:00.015-06:00

Magnificent specimens I am glad to welcome to my blog. These are jaw-dropping, breath-taking minerals, with a beauty beyond this world! Some of those are on sale by Exceptional minerals. The description of each mineral follows the order of the pictures:

Golden Calcite (CaCO3)crystal on Barite (BaSO4)from the Elmwood Mine, Smith County, Tennessee.

Gorgeous deep cherry-red Rhodochrosite (MnCO3) rhombs Trigonal - Hexagonal Scalenohedral with Quartz on Tetrahedrite matrix from the Millennium Pocket of the Fluorite raise, Sweet Home Mine in Alma, Colorado now closed.

The gold on quartz collected from the San Pedro Mine in Santa Fe county New Mexico is on sale for $45,000 USD, I am sure that the gold price of $1,160 US/oz fueled this price tag among its rarity and beauty, just affordable by affluent collectors, or by well funded museums.

Beryl var. Aquamarine (Be3Al2Si6O18)crystal sitting atop bronze Muscovite (KAl2(Si3Al)O10(OH,F)2)blades from Nagar, Aliabad, Hunza Valley, Northern Areas of Pakistan.

Grossular (garnet Ca3Al2(SiO4)3)), and Diopside (CaMg(Si2O6) from Val d'Aosta, Italy.

Apatite / Apatita var. Esparriguina, what a name uh?

2009-09-10T18:45:00.004-05:00

This is a beautiful mineral rarely found in good crystals, this particular one from the Market Hill (Cerro del Mercado) in Durango, state of Durango, Mexico. Variety of this pale yellow specimen is named "Esparriguina."

Apatite is actually three different minerals depending on the predominance of either fluorine, chlorine or the hydroxyl group. These ions can freely substitute in the crystal lattice and all three are usually present in every specimen although some specimens have been close to 100% in one or the other. The rather non-inventive names of these minerals are Fluorapatite, Chlorapatite and Hydroxylapatite. The three are usually considered together due to the difficulty in distinguishing them in hand samples using ordinary methods.

An irony of the name apatite is that apatite is the mineral that makes up the teeth in all vertebrate animals as well as their bones. Get it? Apatite - teeth! Anyway, the name apatite comes from a Greek word meaning to decieve in allusion to its similarity to other more valuable minerals such as olivine, peridot and beryl.

Apatite is widely distributed in all rock types; igneous, sedimentary and metamorphic, but is usually just small disseminated grains or cryptocrystalline fragments. Large well formed crystals though can be found in certain contact metamorphic rocks. Very gemmy crystals of apatite can be cut as gems but the softness of apatite prevents wide distribution or acceptance of apatite as a gemstone.

Let's go technical:
Chemical Formula: Ca5(PO4)3(OH,F,Cl)
Name Origin: Named in 1788 from the Greek apatao - "I am misleading." Reason is that it mislead to confuse for some valuable minerals, such as olivinite, etc.
Crystal System: Hexagonal - Dipyramidal
Cleavage: {0001} Indistinct, {1010} Indistinct
Color: White, Yellow, Green, Red, Blue.
Density: 3.16 - 3.22, Average = 3.19
Diaphaneity: Transparent to translucent
Fracture: Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).
Habit: Colloform - Forming from a gel or colloidal mass.
Habit: Earthy - Dull, clay-like texture with no visible crystalline affinities, (e.g. howlite).
Habit: Massive - Granular - Common texture observed in granite and other igneous rock. Crystal Habits include the typical hexagonal prism with the hexagonal pyramid or a pinacoid or both as a termination. Also accicular, granular, reniform and massive. A cryptocrystalline variety is called collophane and can make up a rock type called phosphorite and also can replace fossil fragments.
Hardness: 5
Luminescence: Non-fluorescent.
Luster: Vitreous (Glassy)
Streak: White

Associated Minerals are hornblende, micas, nepheline and calcite.
Other Characteristics: An unusual "partially dissolved" look similar to the look of previously sucked on hard candy.

Notable Occurrences include Durango, Mexico; Bancroft, Ontario; Germany and Russia.
Best Field Indicators are crystal habit, color, hardness and look.
Radioactivity: Apatite is Not Radioactive

I apologize, took a little while to post another one, been busy. I hope you are doing good.

Best regards,
Oscar G. Shelly

Caramel? no, not at all, fire agate, one of many quartz' forms

2009-02-28T14:51:00.008-06:00

Fire agate

Probably one the most fascinating mineral combinations there is (according to me), hematite and amorphus silica (quartz). I'd say this is the equivalent to an opal, only the iridiscense is not because of water molecules, but because of the iron oxide embedded in the silica. First time I saw one of these specimens - common in Aguascalientes, Mexico - was in college in my Mineralogy class back in 1975 (Faculty of Engineering of the National Autonomous University of Mexico), and I fell off my chair, I was in shock with the beauty of this baby.

Anyhow, I am not sure why this mineral has never made it to precious stone status, but if I ever become president of the Mexico, I'll declare it the stone of the country. If you don't like it as much as I do, don't vote for me.

Ok, let us see what are the fire agate (another form of quartz) life technical specifications:

Chemical Formula: SiO2
Environment: Sedimentary, metamorphic, and igneous rocks.
Locality: Very common mineral found world wide.
Name Origin: From the German "quarz", of uncertain origin according to many, however I heard once that it comes from the old saxonic that means ice very frozen.

Synonyms of quartz:

Agate - banded variety of chaledony
Amethyst - purple
Avanturine - feebly translucent chalcedony
Carnelian - flesh red chalcedony
Cat's Eye - chatoyant
Chalcedony - microcrystalline quartz
Chert - cryptocrystalline quartz
Chrysoprase - apple green chalcedony
Citrine - yellow
Flint - microcrystalline quartz
Hornstone - flint
Jasper - red or brown chalcedony
Moss Agate - variety of chaledony
Plasma - green chalcedony
Prase - leek green chalcedony
Rock Crystal
Rose Quartz - rose colored
Sapphire Quartz - blue colored
Smoky Quartz - brown to black
Tiger Eye - pseudomorph of asbestos

Cleavage: [0110] Indistinct
Color: Brown, Colorless, Violet, Gray, Yellow.
Density: 2.6 - 2.65, Average = 2.62
Diaphaniety: Transparent
Fracture: Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).
Habits: Crystalline - Coarse - Occurs as well-formed coarse sized crystals.
Crystalline - Fine - Occurs as well-formed fine sized crystals.
Druse - Crystal growth in a cavity which results in numerous crystal tipped surfaces.
Hardness: 7 - Quartz
Luminescence: Triboluminescent.
Luster: Vitreous (Glassy)
Streak: White

I hope you enjoy a terrific weekend, today is 2/28/09, visit my website if you have some chance: Oscar el Mexicano

Nominated one of the 100 Best Blogs for Earth Science Scholars

2009-01-01T11:43:00.000-06:00

By: by Bachelors Degree Online

Thanks & Happy New Year!

Oscar G. Shelly

Extinct minerals: Brazilianite...due to mineralogists? or Ice....due to global warming?

2009-01-01T11:29:00.009-06:00

Brazilianite

I read something today (1/1/2009), - Happy New Year by the way - that caught my eye, and it was related to minerals extinction. The article / blog made me wonder if in fact minerals are subject to extinction due to Geological causes, according to Andrew's Geology blog. After serious, and some not so serious thinking, I came up to the following conclusions / examples that I put into consideration for comments / critics.

I believe that is true that some minerals are subject to extinction, due to a variety of causes / phenomena. The first one that comes to mind is the mineral ice. If after all, Al Gore is right with his Global Warming theory, this will be the cause for melting icebergs, glaciers, and the poles in general, which will make ice disappear from the Earth, or better yet: follow one of Newton's laws; thus, ice will be transformed into water and/or vapor. What about snow?

Now, another one that comes to mind is the Brazilianite. A beautiful mineral with a beautiful name too in honor of its country in which it was discovered Brazil. Why does this mineral being so much harder, and stable than ice would disappear from the Earth? well, the disappearance will not be from the Earth, but from the pegmatites of Brazil (at least the ones so far discovered and exploited); Brazilianite specimens have been placed into many Museus and mineralogical collections around the globe, including mine. This is a mineral you don't see anymore in trade shows, so as far as I am concerned, there is another cause for mineral extinction: Avid mineralogists.

Let me take advantage of discussing about this amazing mineral sadly extinct to talk about its mineralogical features as follows:

Chemical Formula: NaAl3(PO4)2(OH)4
Composition: Molecular Weight = 361.91 gm
Sodium 6.35 % Na 8.56 % Na2O
Aluminum 22.37 % Al 42.26 % Al2O3
Phosphorus 17.12 % P 39.22 % P2O5
Hydrogen 1.11 % H 9.96 % H2O
Oxygen 53.05 % O

Name Origin: Named after its first discovery in Brazil.
Crystal System: Monoclinic - PrismaticH-M Symbol (2/m) Space Group: P 21/n
Cleavage: [010] Good
Color: Colorless, Greenish yellow, Yellow green, Light yellow.
Density: 2.98
Diaphaniety: Transparent
Fracture: Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).
Habit: Euhedral Crystals - Occurs as well-formed crystals showing good external form.
Habit: Spherical - Spherical, rounded aggregates.
Hardness: 5.5 - Knife Blade
Luster: Vitreous (Glassy)
Streak: White
Radioactivity: Brazilianite is not Radioactive

Is snow a mineral? Of quartz! just kidding, it's made out of one mineral: ICE

2008-12-13T12:03:00.007-06:00

I haven't have the opportunity of collecting a snow flake to analyze it under the microscope, or simply with a magnifying glass just to make sure I too believe that snow is made out of ice crystals, and that these are considered just like any other specimen, a true mineral! unbelievable uh? Anyhow, this is the hyperlink to a website in which I saw the latest and most astonishing pictures of snow crytals I've ever seen: Snowflakes
.

If someone asked me what is that I learned in the subject of mineralogy about ice as a mineral I can still remember that it has basal cleveage, and therfore, that permits the flow of ice in a glaciar. Is it true? does it make sense? I leave this open for discussion.

Following is the technical data of ice crystals:

Chemical Formula: H2O

Composition: Molecular Weight = 18.02 gm
Hydrogen 11.19 % H 100.00 % H2O
Oxygen 88.81 % O

Environment: Cold weather as snow crystals, coating ponds, glaciers, and icebergs.
Locality: World wide (I don't think someone has ever seen snow in the Sahara Desert though).
Name Origin: From the Middle English "is" or "iis", related to the Dutch "ijs" and German "eis".

Cleavage: None according to many, but it does have basal cleavage
Color: Colorless, Pale blue, Greenish blue, White.
Density: 0.9167
Diaphaniety: Transparent
Fracture: Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments.
Habit: Crystalline - Coarse - Occurs as well-formed coarse sized crystals.
Habit: Dendritic - Branching "tree-like" growths of great complexity (e.g. pyrolusite).
Habit: Massive - Granular - Common texture observed in granite and other igneous rock.
Hardness: 2.5 - Finger Nail
Streak: White
Luminescence: Non-fluorescent.
Luster: Vitreous - Dull

Boleite from El Boleo, Baja California

2008-06-07T18:34:00.005-05:00

This mineral takes me back to 1975, when I took Mineralogy with Professor Raul Ortiz Asiain in the faculty of Engineering of the National Autonomous University of Mexico; he used to bring specimens to class fostering our love for minerals, and boosting the learning process of us, the students. Of course not everyone enjoyed the minerals as much as I did for instance.

I feel lucky I learned so much, and moreover when I was selected professor of the same subject, and I taught it from 1987 until 1989, the year I moved to the USA. Anyhow, I feel it was like a month ago when I saw the first crystal of boleite, its bluish color, its crystallography made a mineral simply unforgettable.

Below is boleite's technical details:

Chemical Formula: KPb26Ag9Cu24Cl62(OH)48
Composition:

Potassium 0.36 % K
Copper 13.94 % Cu
Silver 8.88 % Ag
Hydrogen 0.44 % H
Lead 49.26 % Pb
Chlorine 20.10 % Cl
Oxygen 7.02 % O

Environment: Sedimentary copper deposits. The fugitive presence of K in the formula was determined by microprobe.
Locality: Boleo, Baja California, Mexico.
Name Origin: Named after is locality.
Synonym: Percylite

Cleavage: [001] Perfect, [101] Good
Color: Indigo blue, Light blue.
Density: 4.8 - 5.1, Average = 4.94
Diaphaniety: Transparent to sub translucent
Fracture: Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern.
Habit: Pseudo Cubic - Crystals show a cubic outline.
Hardness: 3-3.5 - Calcite-Copper Penny
Luster: Vitreous - Pearly
Streak: Light green
Estimated Radioactivity from Boleite: Barely detectable

I apologize I took a long break, just changed jobs from Dresser-Rand to T3 Energy, in the meantime I was busy, and traveling like a pilot. I am getting a little bit more relaxed, so thank you for your patience.

I hope you enjoy a terrific weekend, today is 6/7/08, visit my website if you have some chance: Oscar el Mexicano

A picture of a Borealis in a mineral: Labradorite

2008-03-23T12:15:00.009-05:00

Picture: Dual view of a cleavage fragment of labradorite showing the multi-colored labradorescence (schiller effect) and the same area viewed without the color. The color is due to optical interference on the 010 polysynthetic twinning planes (Albite Law).

Next in my blog is tectosilicate "Labradorite" variety: Spectrolite ((Ca,Na)(Si,Al)4O8) in all probabilities named like that in honor of its color spectrum reflected in the tabular crystals as a gift for the eyes. Now, labradorite was named like that thanks to its original locality the Labrador Peninsula. Its beauty combined with its hardness have made the Spectrolite a beloved stone for kitchen tops, and floors.

I remember being in the Telephone company of Saudi Arabia to pay my bill while I lived there back in the 80's, and I was in owe watching such luxury, the whole building was labradorite variety spectrolite, I just couldn't believe it, and at least in those years, it was forbidden to take pictures.

Chemical Formula: (Ca,Na)(Si,Al)4O8
Molecular Weight = 271.81 gm
Empirical Formula: Na0.4Ca0.6Al1.6Si2.4O8
Environment: Magmatic and metamorphic rocks.
Locality: Labrador peninsula, Canada.
Name Origin: Named after its locality.
Synonym: Spectrolite
Crystal system: Triclinic - Pinacoidal
Cleavage: [001] Perfect, [010] Good, [110] Distinct
Color: Colorless, Gray, Gray white, White, Light green.
Density: 2.68 - 2.71, Average = 2.69
Diaphaniety: Translucent to transparent
Fracture: Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern.
Habit: Crystalline - Coarse - Occurs as well-formed coarse sized crystals.
Habit: Granular - Generally occurs as anhedral to subhedral crystals in matrix.
Habit: Striated - Parallel lines on crystal surface or cleavage face.
Hardness: 7 - Quartz
Luminescence: Non-fluorescent.
Luster: Vitreous (Glassy)
Streak: White
Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Labradorite is Not Radioactive

Have a great weekend, once again in Anaco Venezuela, but ready to back to Houston tomorrow morning from Caracas. In the meantime, feel free to visit my website:

Oscar el Mexicano

A picture of a Borealis in a mineral?: Labradorite var. Espectrolite

Pinkier than the Pink Panther - Rhodochrosite

2008-03-22T01:30:00.020-05:00

I am sure that the pink panther's creator was inspired in rhodochrosite (MnCO3) to get that nice color of the funny French cartoon, but, being French, I may be wrong.

Furthermore, the beauty, the habit, and the variety of crystallization make rhodochrosite one of the prettiest, but is one of the softest existing gems in the world, as its hardness is 3 (in the Moss scale of 1 to 10). It means that it can be scratched with a coin, so be real careful (use paper bills instead)!

The fist place (locality) that comes to mind is the one in the Kalahari desert in South Africa, in which the color is beyond a deep pink to almost light cherry red, simply amazing.

South of the Kalahari Desert on the seemingly endless, hot and dust plains of the Northern Cape in South Africa is the Kalahari Manganese Field. The fact that it is estimated to contain 14 billion tons of manganese, not only represents a great economic wealth to the area, but also a paradise to the mineral collector. One hundred and thirty-five minerals have been identified there, since the commencement of mining in the 1940's. Some of the most spectacular Rhodochrosite specimens come from the N'Chwaning II mine, near Kuruman.

Ok, here is the technical data:

Chemical Formula: MnCO3
Molecular Weight = 114.95 gm
Environment: Commonly forms during oxidation of Mn-bearing ores in a carbonate environment.
Locality: Cavnic (Kapnik), Maramures, Romania
Name Origin: From the Greek rhodon -"rose" and chroma - "color."
Synonym: Dialogite
Crystal System: Trigonal - Hexagonal Scalenohedral

Cleavage: [1011] Perfect, [1011] Perfect, [1011] Perfect
Color: Pinkish red, Red, Rose red, Yellowish gray, Brown.
Density: 3.69
Diaphaniety: Translucent to subtranslucent
Fracture: Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments.
Habit: Botryoidal - "Grape-like" rounded forms (e.g.. malachite).
Habit: Columnar - Forms columns
Habit: Massive - Granular - Common texture observed in granite and other igneous rock.
Hardness: 3 - Calcite
Luminescence: None.
Luster: Vitreous (Glassy)
Streak: White
Fluorescence: No

That's it for now, have a Good Friday, and a better Saturday.

Oscar Garcia Shelly.

Is it a candy? no way Jose, it's a Wulfenite

2008-03-15T13:44:00.018-05:00

Yeah, in fact it really looks like a candy, doesn't it? But not so fast my friends, Wulfenite (PbMoO4) may be subject to penalty due to the stiff Clean Air Act mandates, and regulations one of these fine days, as it contains lead and Molybdenum, both chemical elements hazardous to human beings. If you don't believe me, just check on the number of recalls to Chinese-made toys brought back to China, because of their lead content. God help us.

At any rate, secondary mineral Wulfenite is another interesting specimen, found in oxidation and enrichment zones with high saturation of lixiviated chemical elements from their original ore deposit, just like adamite, legrandite, hemimorphite, and goethite.

Wulfenite is abundant in Mexico (Chihuahua and Sonora), and in other areas of the world, such as the state of Arizona, in the USA, and the land of the dioptase: Tsumeb, in Namibia, Africa. Most beautiful crystals come from all these places, just like a contest, you never know which is producing a better looking one for the delight of the most avid mineralogist including yours truly.

Ok, how about if you take a look at the various features of Wulfenite including its name origin as follows:

Chemical Formula: PbMoO4
Molecular Weight = 367.14 gm
Environment: Secondary lead mineral. Forms a series with stolzite.
Locality: Bleiberg, Villach, Kärnten (Carinthia), Austria; Los Lamentos Mine in Municipio of Ahumada, Chihuahua Mexico; also in the San Francisco Mine, near Cucurpe in Sonora, Mexico, and so on.
Name Origin: Named after the Austrian mineralogist, Frantz Xaver von Wulfen (1728-1805).
Crystal System: Tetragonal - Dipyramidal
Cleavage: [101] Imperfect
Color: Orange yellow, Waxy yellow, Yellowish gray, Olive green, Brown.
Density: 6.5 - 7, Average = 6.75
Diaphaniety: Subtransparent to subtranslucent
Fracture: Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments.
Habit: Massive - Granular - Common texture observed in granite and other igneous rock.
Habit: Tabular - Form dimensions are thin in one direction.
Hardness: 3 - Calcite
Luminescence: None.
Luster: Resinous - Greasy
Streak: Yellowish white

It's weekend time, I am in Anaco, and it's time to go to have dinner in Venezuela, and I think that maybe a couple or arepas, or cachapas with parchita juice will make it. Bon apetite amigos, have a terrific weekend.

Oscar el Mexicano

Proustite - As red as Hugo Chavez' revolution

2008-03-12T21:16:00.012-05:00

Proustite, tricky reading of such a beautiful mineral that consists of sulfur, arsenic and silver (Ag3AsS3). However, its color is as magnificent as a rubi, or as a red garnet (pirope), or as a cuprite, a beauty just out of this world. Just see the picture on your right, which by the way, is a specimen from Chañarcillo, in Atacama, Chile. Among other features, the rarity of proustite is that being a sulfide, the crystals are not metallic, but semi-metallic, and glassy and weak as a wulfenite, or a rodochrosite.

Fine proustite crystals, with their transparency, luster and color, are very attractive mineral specimens. However, just as with other silver minerals, it is sensitive to light, and it can form a white coating upon light exposure. This coating can be cleaned off, but fine specimens should be stored in closed containers with limited or no light exposure.

Proustite is usually found in the same ore veins with pyrargyrite (consisting of sulfur, antimony and silver), and other silver sulfides. Proustite and Pyrargyrite are iso-structural, in other words, both minerals have the same structure but with a different chemistry (proustite has antimony, and pyrargyrite has arsenic).

Chemical Formula: Ag3AsS3
Molecular Weight = 494.72 gm
Composition: Silver 65.41%; Arsenic 15.14%; Sulfur 19.44%
Environment: Late forming mineral in hydrothermal deposits, in the oxidized and enriched zone, associated with other silver minerals and sulfides.
Locality: Himmelsfurst mine, Erbisdor, near Freiberg, Germany; Chañarcillo mine in Atacama, Chile; Chihuahua, Mexico.
Name Origin: After the French chemist, J. L. Proust (1755-1826).
Crystal System: Trigonal - Hexagonal Scalenohedral
Cleavage: None
Color: Vermilion, Reddish gray.
Density: 5.5 - 5.6, Average = 5.55
Diaphaniety: Transparent to translucent
Fracture: Brittle - Sectile - Brittle fracture with slightly sectile shavings possible.
Habit: Blocky - Crystal shape tends to be equant (e.g. feldspars).
Habit: Crystalline - Poor - Occurs primarily as crudely formed crystals.
Habit: Massive - Uniformly indistinguishable crystals forming large masses.
Hardness: 2-2.5 - Gypsum-Finger Nail
Luminescence: None.
Luster: Sub Metallic
Magnetism: Nonmagnetic
Streak: Vermilion red

Greener than an emerald? no, but...prettier? oh yes - Dioptase

2008-03-10T12:38:00.025-05:00

(Upper picture: Dioptase on dolomite crystals. Lower picture: Emerald).

It was just a matter of walking through some of the many displays in the 1979 Tucson Gem & Mineral Show, that I had already spent (mentally) around $2 million dollars in specimens, many of which simply took my breath away.

It was the first time I had the opportunity to attend this magnificent world class event, and my first time in the United States, what a great trip. Flew in an American Airlines Boeing 707 Mexico City-Tucson via Dallas, TX, my English was lousy, but I managed to get JIT (just in time) for the connection. Once in Tucson, Arizona, all was easier, nicer, got to the show so excited I wanted them all. But this time, though I dedicate the remembrance to the dioptase, (even its name is lovable). I met in Tucson with my college Mineralogy Professor Dr. Raul Ortiz Asiain and his daughters (Violeta, Magnolia, Dalia and China), all mineral experts, so we had a good time talking about minerals day and night for 3 days in a row eating McDonalds hamburguers on a non-stop basis either.

Didn't bring much money, about $300 dollars, even though it was sufficient to buy some, my budget was limited, because I still had to pay for hotels, meals (McDonalds), and transportation. One of the specimens I bought in the show ($10 US) was a superb nice combination of copper silicate (dioptase) on dolomite, both minerals of the same crystal system (Trigonal - Rhombohedral). The beauty of those cyclosilicate dioptase crystals is not easy to describe, other than its dark blue green, glassy in luster, transparent, well-formed coarse crystals features; I'd say this specimen is prettier than many emeralds I've seen, (which is too adventurous for some), but I admit my weakness for the dioptase, a mineral I thought it was an emerald, but ended up being originally from Tsumeb, Namibia, and not an emerald, but a dioptase. This is the story:

Late in the 18th century, copper miners in Kazakhstan thought they've found an emerald deposit. They found cavities in quartz veins in a limestone, filled with thousands of lustrous emerald-green transparent crystals. The crystals were sent to Moscow, Russia for analysis. However the mineral's inferior hardness of 5 compared with emerald's greater hardness of 8 easily distinguished it. Later, in 1797, René Just Haüy (famous French mineralogist) determined that the "emerald-like" Kazakhstani mineral was in fact not emerald, but a new mineral in science and named it dioptase (Greek, dia, "through" and optima, "vision"), as a consideration to the two cleavage directions of the dioptase, visible inside fine crystals.

Ok, this is the technical data of Dioptase:

Chemical Formula: CuSiO2(OH)2
Molecular Weight = 157.64 gm
Environment: Secondary mineral in oxidized zones of copper deposits.
Locality: Tsumeb and Cochab, Namibia; Altyn Tube, Russia.
Name Origin: From the Greek, dia - "through" and optomai - "vision."
Crystal System: Trigonal - Rhombohedral
Cleavage: [1011] Good
Color: Dark blue green, Emerald green, Turquoise.
Density: 3.28 - 3.35, Average = 3.31
Diaphaniety: Transparent to translucent
Fracture: Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).
Habit: Cryptocrystalline - Occurs as crystals too small to distinguish with the naked eye.
Habit: Crystalline - Coarse - Occurs as well-formed coarse sized crystals.
Habit: Massive - Uniformly indistinguishable crystals forming large masses.
Hardness: 5 - Apatite
Luminescence: None.
Luster: Vitreous (Glassy)
Magnetism: Nonmagnetic
Streak: Green

I wish you a terrific week, trouble free, and productive. In the mean time, till' my next posting, I hope you learned a bit more about the wonderful mineral world.

Best regards,

Oscar el Mexicano

PD: By the way, my return from that 1979 first visit to the Gem & Mineral Show in Tucson was via Aeromexico that used to stop in Hermosillo, Cd. Obregon, Culiacan, Guadalajara and finally Mexico City, an almost 8 hrs. trip!!!