Saturday, December 13, 2008

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

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

Saturday, June 7, 2008

Boleite from El Boleo, Baja California

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

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

Sunday, March 23, 2008

A picture of a Borealis in a mineral: Labradorite

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

Saturday, March 22, 2008

Pinkier than the Pink Panther - Rhodochrosite

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.

Saturday, March 15, 2008

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

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

Wednesday, March 12, 2008

Proustite - As red as Hugo Chavez' revolution

Proustite, tricky reading of such a beautiful mineral that consists of sulfur, arsenic and silver (Ag3AsS3). However, its color as red as Hugo Chavez' flag 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 redHugo Chavez

Monday, March 10, 2008

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

(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!!!

Saturday, March 1, 2008

Violets are blue, and so are you: Amethyst!

Isn't that amazing that some minerals can be found in so many different forms, colors, varieties, locations and ore deposits? such is the case of Tectosilicate Quartz (SiO2), an old German / Saxony's word that meant ice very frozen.

Quartz is the most abundant mineral in the surface of the world, found in almost each and every type of rock, or by itself in geodes, or cavities in acidic volcanic lavas, or magmas. However, one of the prettiest of all quartz varieties is the purple or violet colored gemstone, known as "amethyst" a semi-precious stone beloved by many people, including me.

For a mineralogist, the value of an amethyst comes from its degree of crystallization, color and size. The deeper the color, the larger the size, and the most perfect its crystals are, among other features makes it more valuable, and even appreciated in a Museum of Natural History.

The name "Amethyst" comes from the Greek "amethos" or alcohol. The following story is not well known, but I learned it from Professor Raul Ortiz Asiain (for me, the best Mineralogist in Mexico of all times), that people that eat amethyst dust did not suffer of hang over after drinking heavily the night before. I never tried such a recipe, because first of all I don't drink; I haven't heard this anywhere else in the world, and Professor Ortiz Asiain passed away more than 10 years ago, rest in peace.

Anyhow, let us go technical:

Chemical Formula: SiO2
Molecular Weight = 60.08 gm
Environment: Sedimentary, metamorphic, and igneous rocks.
Locality: Very common mineral found world wide.
Name Origin: From the German "quarz", of uncertain origin.
From the same chemical formula:

Agate - Banded variety of chalcedony
Amethyst - Purple
Avanturine - Feebly translucent chalcedony
Carnelian - Flesh red chalcedony
Cat's Eye - Chatoyant
Chalcedony - Micro crystalline quartz
Chert - Crypto crystalline quartz
Chrysoprase - Apple green chalcedony
Citrine - Yellow
Flint - Micro crystalline quartz
Hornstone - Flint
Jasper - Red or brown chalcedony
Moss Agate - Variety of chalcedony
Plasma - Green chalcedony
Prase - Leek green chalcedony
Rock Crystal - Transparent
Rose Quartz - Rose colored
Sapphire Quartz - Blue colored
Smoky Quartz - Brown to black
Tiger Eye - Pseudomorph of asbestos

Crystal System: Trigonal - Trapezohedral
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).
Habit: Crystalline - Coarse - Occurs as well-formed coarse sized crystals.
Habit: Crystalline - Fine - Occurs as well-formed fine sized crystals.
Habit: Druse - Crystal growth in a cavity which results in numerous crystal tipped surfaces.
Hardness: 7 - Quartz
Luminescence: Triboluminescent.
Luster: Vitreous (Glassy)
Streak: White

Ok, enough I think, by now I am sure you are an expert in Amethyst and its mother quartz. By the way, the only joke I remember about quartz goes like this: Dad (a little quartz talking to his father), is it true that we precipited out of solution? Dad answers: Of Quartz!

Have a terrific weekend, and in the meantime, you may want visit my website where you can find a nice picture of the day taken by me somewhere in the world with my nice Nikon D40X: Oscar el Mexicano

Monday, February 25, 2008

A mineral, or lemon pie filling? - Adamite

Adamite (Zn2(AsO4)(OH) (or hydroxide zinc arseniate) is another beautiful mineral that is found in several locations around the world (Mexico, Chile, Namibia, etc.) in ore deposits rich in zinc, lead, and arsenic that have suffered oxidation, due to weathering and lixiviation, out of the percolating water. All the sulfides decompose, and the resulting rich-in-chemical elements low-temperature solution deposits near and beneath the original ore. One of the formed new minerals is a shiny and crystallized piece of art with a green color that varies considerably. The most beautiful specimens I have had the chance to collect come from the Ojuela Mine in Mapimi, state of Durango. Adamite is found hereby associated with hemimorphite, legrandite, goethite, limonite, cobalt-adamite (purple), calcite, pyrite, cuprite, malachite, hematite, and others I am sure I don't remember. If someone asked me to make does an Adamite crystal looks like to me, I'd say it does look like filling of a lemon pie, the one it used to be cooked from scratch by my late Grandmother in Guadalajara (fattening, but out of this world!).

Chemical Formula: Zn2(AsO4)(OH)

Zinc 45.61 % Zn 56.78 % ZnO
Arsenic 26.13 % As 40.08 % As2O5
Hydrogen 0.35 % H 3.14 % H2O
Oxygen 27.90 % O

Molecular Weight = 286.71 gm
Locality: Ojuela Mine, Mapimi Durango Mexico; Chile, Atacama, Chañarcillo
Name Origin: Named after the French mineralogist Gilbert Joseph Adam (1795-1881).

Crystal System: Orthorhombic - Dipyramidal
Cleavage: [101] Good, [010] Poor
Color: Yellow, Green, Violet, Pink, Yellowish green.
Density: 4.3 - 4.5, Average = 4.4
Diaphaniety: Subtransparent
Fracture: Brittle - Generally displayed by glasses and most non-metallic minerals.
Habit: Druse - Crystal growth in a cavity which results in numerous crystal tipped surfaces.
Habit: Encrustations - Forms crust-like aggregates on matrix.
Habit: Tabular - Form dimensions are thin in one direction.
Hardness: 3.5 - Copper Penny
Luminescence: Fluorescent and phosphorescent.
Luster: Vitreous - Resinous
Streak: white
Fluorescent: Yes, crystals fluoresce green under SW ultra violet light

I hope you have a productive week, visit if you have a chance my updated website: Oscar el Mexicano, meantime, see you in my next posting.

Saturday, February 9, 2008

Fool's gold

I was around 9 years old, when I saw the first pyrite specimen in my life, and I remember I was so greatly impressed, that I wanted to go to the site where the person that showed it to me (a neighbor by the name of Javier Garcia) said he had collected the piece from, the "Cerro del Cuatro" (the hill of the four) in Guadalajara, state of Jalisco in Mexico.

From that day, I fell in love with minerals; and soon enough, my dad discovered I had a new hobby, and bought a Mineralogy booklet for the family, which contained, among others, some pictures of perfect pyrite cubes crystals from Rio Tinto, Spain. I was hooked, and eager to learn more and more about pyrite and other minerals. Pyrite was, at any rate, the mineral that changed my life, with its luster and a perfect crystallization. I would've probably be a doctor, or a pilot, but not a geologist otherwise, thanks to Pyrite.

One of the first things I learned about pyrite was that its origin was related to volcanoes, and that it had a funny nickname: "fool's gold," due to its brassy yellow color, and metallic luster resembling gold to some. How many people bought pyrite in lieu of gold just to find later on they have been fooled? maybe a good bunch, but such is life.

Anyhow, let's see what is this fool's gold or pyrite consist of:


Chemical Formula: FeS2
Composition: Iron (Fe) 46.55%; Sulfur (S) 53.45%
Molecular Weight = 119.98 gm
Empirical Formula: Fe2+S2 (Iron sulfide)
Environment: Sedimentary, magmatic, metamorphic, and hydrothermal deposits.
Locality: I collected beautiful crystals from Naica, Chihuahua, and Fresnillo, Zacatecas, as I used to work for Cia. Fresnillo, SA between 1977 and 1980. But pyrite is common on a world wide basis, related to almost any kind of ore deposit.
Name Origin: From the Greek, pyros - fire and lithos - stone or mineral, "stone which strikes fire," in allusion to the sparking produced when iron is struck by a hammer, or by a lump of pyrite

For more technical details, please refer to:

In the meantime, have a great weekend, see you in my next posting.


Oscar Garcia Shelly

Sunday, February 3, 2008

There are only four precious stones in the world!

There are only four (4) precious stones in the world, contrary to what many people believe. The word precious has evidently two meanings - and both being adjectives - can definitely confuse even to the most knowledgeable person. The funny thing about it, is that some varieties of these precious stones may be as pretty, and even more expensive than a precious stone. The value of these specimens is a function of their purity, quality, color, perfection of its crystals, size, durability (thanks to their hardness), and so forth. So don't be surprised next time you see an opal from Coober Pedy Australia in or around thousands of dollars.

In summary, these are the only four precious stones in the world, everything else even though look precious, are semiprecious stones. Of course, for the mineralogist, and experience rock collector, there are also semi-ugly and very ugly stones (good to practice pitching). What makes them gain such qualification is the opposite of the adjectives of a precious stone. Following are the only four precious stones in the world:

Diamond (multi color, sapphire (blue), emerald (green) and ruby (pink to red). Following is the description of each and every one.


Chemical Formula: C
Composition: Carbon 100.00%
Molecular Weight = 12.01 gm
Environment: Gas rich, ultra-basic diatremes from mantle depths (>30 km), and alluvial placer deposits derived from the Kimberlite (in honor of Kimberley, South Africa) rocks. Kimberlite consists of olivine, garnet, pyroxene, and calcite.
Localities: Kimberly, republic of South Africa. India. Brazil. Ural Mountains, Russia. Murfreesboro, Arkansas, USA.
Name Origin: From the Greek, adamas, meaning "invincible" or "hardest."


Chemical Formula: Al2O3
Composition: Aluminum 52.93% and Oxygen 47.07%
Empirical Formula: (Al2O3)
Environment: Contact and regionally metamorphosed rocks.
Locality: Tchainit and Yakutia, Russia.
Name Origin: Probably derived from the Sanskrit, kuruvinda, meaning "ruby."
Synonym: Leucosapphire - colorless (I do not agree, but that is what you find in the Dana classification). If it does not have the beautiful blue color, it's just plain and simple: is everything, but a sapphire!

Soon Emerald and Rubi.

In the meantime, have a wonderful weekend, the remaining of it, and enjoy the super bowl.

Best regards,

Oscar G. Shelly

Sunday, January 27, 2008


Legrandite is one of my favorite minerals, first of all, is a rare specimen with a single worldwide location, and that is the "Ojuela Mine" in Mapimi, state of Durango in Mexico, a mine I had the chance to visit several times during 1985, and from where I collected other related minerals, such as Adamite, cobaltoadamite, goethite, malachite, hemimorphite, wulfenite, etc.

The name "legrandite: is in honor of the Ojuela's first mine superintendent in the late 1800's, Monsieur Legrande, a mining engineer from Belgium.

The most beautiful legrandite specimen I've ever seen, was in what is now the Museum of Mineralogy in Tehuacan, Puebla, founded by a passed friend of mine Mr. Miguel Romero (Mexican Congressman in the late 80's). The years I taught Mineralogy (1987-1989), I used to take my Mineralogy students to see Mr. Romeros' mineral museum, and they loved the beauty, variety and quality of this collection. Those trips were very educative field trips that I of course enjoyed as well.

This is the URL to the museum in case you'd like to visit:, I plan to do that as soon as feasible.

Chemical Formula:
Zn2(AsO4)(OH)·(H2O) - Hydrated Zinc Arsenate Hydroxide

Environment: Secondary mineral in zinc ore bodies.
Locality: Ojuela mine near Mapimi, Durango.

More data:
I own some of these specimens, one I consider of superb high quality, will publish the picture one fine day.
In the meantime, have a good day, and I see you on my next post.

Wednesday, January 16, 2008

XXI century's gold rush

This is my new blog, I hope you enjoy the topics. I will discuss minerals, localities, names, origins, and links to sites, so that you can discover the beautiful world of Mineralogy, and its intrinsec relation with the global economy.

I hold a BS in Geological Engineering from the Faculty of Engineering of UNAM ( in Mexico City, wherein, I taught the subject of Mineralogy back in the late 80's. I served as Vicepresident of the Mexican Mineralogical Society, and moved to the USA in 1989 to work for Cooper Industries as Sales Manager for Latin America. I completed an MBA from Devry University in Houston, Texas in June 2007.

Allright, enough with the presentations, let's move foreward, and start the blog. I'll start discussing one of the most precious metals on earth: Gold.

Gold / Oro (Spanish for gold)
Name Origin: Anglo Saxon, of uncertain origin.
Chemical Formula: Au
Composition: Gold 100.00 % Au
Molecular Weight = 196.97 gm
Quartz veins and alluvial deposits.
Locality: Sierra Nevada Mountains, Nome, Alaska and many other places in the world. Link to for more location Data.

XXI Gold rush

Is the gold rush here to stay, or will our money invested in such precious metal remain flat for years to come, just the way it happened during the 80's and 90's? Is it true that gold is a great investment when there is an ongoing war? One thing is for sure: gold is going up in price, beating new records, but even so, my recommendation after careful review, for those that have some surplus money: diversify! invest just a portion of your money in gold; don't put all the eggs in one basket.

This is a good website to check the price of gold: and if you like the song "Gold" check it out: this was a song performed by the Spandau Ballet in the 80's.

Happy 2008.

Any comments?