Dunite

About it

Peridotite that is over 90 per cent olivine: a sugary green rock that weathers to a tan crust. Named for Dun Mountain, New Zealand; often hosts chromite, and is quarried for olivine at Twin Sisters, Washington.

Type

Rock (igneous)

Group

Igneous (ultramafic plutonic)

Specific gravity

3.2–3.4

Lustre

vitreous (glassy)

Colours

olive green, yellow-green, tan-brown when weathered

Transparency

opaque

Typical values: real specimens vary. For more, see mindat.org.