THE MINERAL CROCOITE

Chemistry: PbCrO4 , Lead Chromate
Class: Sulfates
Subclass: Chromates
Uses: Only as mineral specimens and as a minor ore of chromium.
Specimens

Crocoite is a rather unusual lead mineral and can be a beautiful and colorful specimen. Crocoite provides a nice color to the mineral kingdom and is well known for its distinctive orange-red color. Its main source of quality specimens comes from the Dundas District of Tasmania, Australia. The crystals there are usually long thin prisms. However, large crystals from this locality have been scarce in the past thirty years. Most specimens do not have any crystals over 5 cm long. Crocoite's high density and luster are the result of its lead content. Some crocoite aggregates are composed of bars and splinters, of differing sizes, going in a dozen different directions and produces a certain character to these specimens that is distinctive of crocoite. Crocoite is also one of the very few chromate minerals. Beautiful specimens that show off crocoite's unique color, high luster and unusual character are a prized addition to anyones collection.

PHYSICAL CHARACTERISTICS:

Color is bright orange-red to yellowish-red.
Luster is adamantine to greasy.
Transparency: Crystals are translucent to transparent.
Crystal System is monoclinic; 2/m
Crystal Habits include prismatic crystals somewhat square in cross-sections, often striated lengthwise. Terminations are usually poorly developed and appear uneven or pitted. Also, granular and columnar.
Cleavage is distinct in two directions lengthwise, prismatic.
Fracture is conchoidal and uneven.
Hardness is 2.5 - 3.
Specific Gravity is approximately 6.0+ (very heavy for translucent minerals)
Streak is orange-yellow.
Other Characteristics: Index of refraction is a very high 2.36
Associated Minerals are wulfenite, pyromorphite, cerussite, limonite and vanadanite.
Notable Occurrences include Dundas District, Tasmania, Australia; Ural Mountains, Russia and Inyo and Riverside Counties in California, USA.
Best Field Indicators are crystal habit, locality, density, high luster and color.