The Mineral OSBORNITE

Chemistry: TiN, Titanium Nitride
Class: Native Elements
Subclass: Nitrides
Series: Osbornite-Sinoite
Uses: Only as mineral specimens.
Specimens

Osbornite is one of the rarest minerals from Earth. This can be said because it is not found in terrestrial rocks. Osbornite is only found in enstatite chondrite meteorites. These stoney meteorites contain minerals that have been extremely reduced, the opposite of oxidized. Other chemically unusual minerals that are found in these meteorites include sinoinite {SiNO}, cohenite {Fe₃C}, schreibersite {(Fe, Ni)₃P}, oldhamite {CaS} and troilite {FeS} as well as plagioclase, enstatite and about 10-15% iron-nickel. How osbornite forms and what produces these chemically unusual meteorites is still being studied.

Although osbornite is a compound and not an element, it is still classified in the Native Elements Class as an elemental compound (an oxymoron for sure). This is basically because it is difficult to put in any other class! Since it lacks oxygen or halides, it can not be classified in any class except the elements or the sulfides. Although it lacks sulfur, it could have been classified as a sulfide as the arsenides are. But osbornite's chemical bonds are more similar to the chemical bonds in elements like sulfur and other elemental compounds such as moissanite, carlsbergite, nierite. And so we get the unsual situation were compounds such as osbornite are classified as elements.

PHYSICAL CHARACTERISTICS:

Color is bronze yellow to golden yellow.
Luster is metallic.
Transparency: Crystals are opaque.
Crystal System is isometric; 4/m bar 3 2/m.
Crystal Habits include small disseminated grains in meteorites.
Hardness is 7.
Specific Gravity is 5.3 - 5.4 (above average for metallic minerals)
Associated Minerals include iron-nickel, sinoinite, cohenite, schreibersite, oldhamite, troilite, plagioclase and enstatite
Notable Occurrences include Gorakhpur, Basti district, Uttar Pradesh, India; the site at which the Bustee meteorite was found and other enstatite chondrite meteorite sites.
Best Field Indicator is color, source, associations and density.