THE MINERAL OTAVITE

Chemistry: CdCO₃, Cadmium Carbonate.
Class: Carbonate.
Group: Calcite.
Uses: A minor ore of cadmium and as mineral specimens.
Specimens

Otavite is a rare mineral from the famous mines of Tsumeb, Otavi (hence the name), Namibia. It is one of only a few cadmium minerals as cadmium is usually a trace element in other minerals. Other cadmium minerals include: Native elemental cadmium; the oxide mineral monteponite; the sulfide minerals greenockite, hawleyite, cadmoselite, shadlunite, barquillite, cernyite and quadratite; the sulfate mineral niedermayrite, and the arsenate minerals andyrobertsite, and keyite. All are rare minerals, as is otavite. Otavite is a member of the Calcite Group of minerals. Most other members of this group are quite common and include such well known minerals as calcite, siderite, rhodochrosite, smithsonite and magnesite.

PHYSICAL CHARACTERISTICS:

Color is usually white, but can also be yellowish brown, reddish brown and brown.
Luster is adamantine to pearly.
Transparency crystals are usually translucent to transparent.
Crystal System is trigonal; bar 3 2/m.
Crystal Habits are limited to crusts and tiny scalahedral crystals.
Cleavage is perfect in 3 non-perpendicular directions forming rhombs.
Fracture is conchoidal.
Hardness is 3.5 - 4.
Specific Gravity is 5 (very heavy for a translucent mineral).
Streak is white.
Other Characteristics: Effervesces with acid and some specimens have fluoresced red under shortwave UV light.
Associated Minerals includes azurite, malachite, smithsonite and calcite.
Notable Occurrences include the type locality of Tsumeb, Otavi (hence the name), Namibia; Blanchard Mine, New Mexico, USA and Broken Hill, New South Wales, Australia.
Best Field Indicators are density, reaction to acids, cleavage, color and locality.