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

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.

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