San Carlos peridotite with chrome diopside and spinel in volcanic basalt Fossil The glossy schorl crystals grow

The glossy schorl crystals grow in short prisms with the classic trigonal 'Mercedes' termination characteristic of Erongo material

The specimen also has an interesting snowball of small colorless needles atop the hyalite

tabular crystals which can display parallel growth and twinning

I suspect the black material could be poorly-formed specularite hematite

and is very bright when exposed to a powerful 365nm UV light

San Carlos peridotite with chrome diopside and spinel in volcanic basalt Fossil The glossy schorl crystals growLocale: San Carlos Apache Reservation, Arizona Approx dimensions: 3 x 2. 5 x 2" Approx weight: 260g While this material is commonly called peridot in (or on) basalt, it is actually more complex. It would be more accurately called a peridotite xenolith in basalt. Peridot is the gem quality version of the mineral olivine, which is common in our Earths upper mantleand even in space. In comparison, peridotite is a combination of several types of minerals