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Download hereGENERAL DESCRIPTION
Crocoite is a rare lead chromate. It can be found only in the oxidation zones of the lead-containing deposits where the surrounding rocks contain chromium.
The crocoite crystals, almost always prismatic, very lengthened and finely striated, are generally joined together in acicular aggregates. Their colour is orange red rather sharp.
Crocoite is a very fragile mineral, which must be handled with delicacy. Crocoite is also photosensitive and tends to brown and fade with light.
Relative great quantities of crocoite were extracted from the deposits of the district of Beresovsk in Russia. Currently, the most exceptional specimens come from Dundas in Tasmanie, Australia. This last locality discovered crystals measuring several centimetres.
In France, crocoite was discovered out of millimeter-length crystals in the Cantonnier lead vein, near of Nontron in the Dordogne and in Goutelle (area of Pontgibaud, Puy-de-Dôme).
The co-types of this species are kept at the Muséum national d'Histoire naturelle de Paris in the Haüy collection. The sample comes from the Tsvetnoi mine in the Uspenskaya Mounts, i.e. the complex of gold mines of Berezovskoye (Berezovsk or Beresov) with 18 kms in the North-East of Ekaterinburg (Yekaterinburg; Sverdlovsk) in the Ural Mountains in Russia. Beudant published this new species in 1832. The chemical co-type, sample in which Vauquelin discovered the element chromium plates (Cr) in 1797 is also deposited in the collections of mineralogy of the Muséum national d'Histoire naturelle de Paris.
Did you know? Because of its relative abundance in certain mines of Russia and Tasmanie, crocoite was mined for to produce lead and yellow-orange pigments.
HISTORY : Name inspired from the Greek word "κροκοσ" [krokos] meaning saffron, because of its color
Species first discovered in 1761 by Johann Lehmann (German mineralogist) in the Ural Mountains and described in 1832 by François-Sulpice Beudant, French mineralogist
Type-locality: Beresovsk, Yekaterinburg (Sverdlovsk), Russia
ANCIENT NAME : Plomb rouge, plomb chromaté
CHEMICAL FORMULA : Pb CrO4
CRYSTAL SYSTEM : Monoclinic
COLOR : Orangeish red, orange
DIAPHANIETY : Transparent to translucent
LUSTER : Adamantine
STREAK : Yellow-orange
MORPHOLOGIE : Prismatic crystals, striated, forming aggregates
HARDNESS : 2,5-3,0
CHEMICAL CLASS: 6,1
DENSITY : VI - Sulfates, chromates, tungstates and molybdates
GROUP : Crocoite
STRUNZ CLASS BEFORE 2001 : 6/F.01-30
STRUNZ CLASS AFTER 2001 : 7.FA.20
