Click on a letter above to view the list of gems.  

Crocoite
Current inventory:  1 gem
 

Chemistry:  PbCrO₄

Discovered in 1832;   IMA status: Valid (pre-IMA; Grandfathered).
Crocoite gets its name from the Greek word krokos, meaning crocus or saffron, in allusion to its distinctive red-orange color.

Classification

Mineral Classification:

Chromates

Strunz 8th Ed. ID:

6/F.01-30

6 : Sulphates, Chromates, Molybdates
F : Chromates [CrO4]2-
01 : Tarapacaite - Crocoite series

Crystal Data

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

As prismatic to acicular crystals with nearly square outline, elongated and striated, to 15 cm; short prismatic to pseudo-octahedral, may be highly modified, terminations are commonly hollow or incomplete. Typically in radial sprays to randomly intergrown aggregates.

Twinning:

None

Physical Properties

Cleavage:

[110] Distinct, [001] Indistinct, [100] Indistinct

Fracture:

Irregular, Uneven, Conchoidal

Tenacity:

Brittle, Sectile

Hardness (Mohs):

2.5 - 3.0

Density:

5.97 - 6.06 (g/cm³)

Luminescence:

Weak; reddish to dark brown in SW UV; weaker effect in LW UV

Radioactivity:

Not Radioactive

Optical Properties

Color:

Yellow, Orange, Red Orange, Red

Transparency:

Translucent to Transparent

Luster:

Adamantine, Vitreous

Refractive Index:

2.290 - 2.660  Biaxial ( + )

Birefringence:

0.370 (very high)

Dispersion:

Very Strong; r > v

Pleochroism:

Weak; X = Red-Orange; Y = Red-Orange; Z = Blood Red

Occurances

Geological Setting:

An uncommon secondary mineral in the oxidized portions of lead deposits associated with chromium-bearing rocks; may be of post-mine formation.

Type Locality:

Tsvetnoi Mine, Uspenskaya Mt, Berezovskoye Au Deposit (Berezovsk Mines), Berezovskii (Berezovskii Zavod), Ekaterinburg (Yekaterinburg; Sverdlovsk), Sverdlovskaya Oblast', Urals Region, Russia

Year Discovered:

1832

View mineral photos:

Crocoite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Crocoite is a relatively rare mineral but an extremely rare gem. It is very soft with a Moh's hardness of only 2.5 - 3.0 and has a very high dispersion, but this is masked by the intense color. Its density is extremely high at 5.97 - 6.06 due to its lead (Pb) content of about 64% and cromium (Cr) content of about 16%. Crocoite's intense reddish-orange color is almost unique in the gem world and makes this extremely rare gem even more desirable.

The best known source for exceptional specimens is the Adelaide and other mines, Dundas district, Tasmania, Australia. Other sources of Crocoite are the Tsvetnoi mine, Mt. Uspenskaya, the Preobrazhensky mine, and other mines, Beresovsk district, and on Mt. Tochil’naya, Middle Ural Mountains, near Yekaterinburg (Sverdlovsk), Russia; fine examples from Obercallenberg, near Glauchau, Saxony, Germany; the Argent Pb–Zn mines, about 100 km east of Johannesburg, Transvaal, South Africa; in the USA, from Darwin, Inyo County, California; at the Moon Anchor, Potter-Kramer, Pack Rat, and other mines south of Wickenburg, Maricopa County, Arizona.
 

  
Crocoite gems for sale: