THE MINERAL OLIVENITE

Chemistry: Cu2AsO4(OH), Copper Arsenate Hydroxide
Class: Phosphates
Uses: As mineral specimens and minor ore of copper.
Specimens

Olivenite is a rare secondary copper mineral that is noted for its deep olive green color, hence the name. It is found in deeply weathered, highly concentrated copper sulfide ore bodies. Olivenite is isostructural with the minerals libethenite, Cu2PO4(OH) and adamite, Zn2AsO4(OH). This means that they share the same symmetry and crystal shapes. Olivenite's olive green color and bright luster make it a popular mineral specimen.

PHYSICAL CHARACTERISTICS:

Color is dark olive green.
Luster is resinous to nearly adamantine.
Transparency: Specimens are translucent to almost opaque.
Crystal System is orthorhombic 2/m2/m2/m
Crystal Habits include crystals that are diamond-shaped, often acicular, prisms that are terminated by a dome with triangular faces. Can form feniform masses similar to wavellite's typical habit. Also as tiny crystalline druzes, fiberous masses, nodules and crusts.
Cleavage is poor in two directions, but rarely noticed.
Fracture is conchoidal.
Hardness is 3
Specific Gravity is approximately 3.9 - 4.4 (above average to heavy for translucent minerals)
Streak is olive green.
Associated Minerals are malachite, libethenite, Clinoclase, limonite, adamite, agardite and other secondary copper ore minerals.
Other Characteristics: Soluable in hydrochloric acid.
Notable Occurrences: Cornwall, England; Nevada, USA and Tsumeb, Nambia.
Best Field Indicators are color, habits, soluability in hydrochloric acid, associations, locallities and density.