Riebeckite

Description

Riebeckite has a hardness of 5 – 5 and a specific gravity of around 3.44. It was first described in 1888 for an occurrence on Socotra Island, Aden Governorate, Yemen, and was named for Emil Riebeck, a German explorer, ethnologist, and mineralogist.

It’s found in roughly a couple hundred locations worldwide on every continent, with 23 locations in Colorado, often near “alcalic granites, syenite and undersaturated rocks. Rarer in felsic volcanics and granite pegmatites; also in some schists” according to Mindat. It occurs in association with aegirine, nepheline, albite, arfvedsonite in igneous rocks; with tremolite, ferro-actinolite in metamorphic rocks; and with grunerite, magnetite, hematite, stilpnomelane, ankerite, siderite, calcite, chalcedonic quartz in iron formations. It’s found in at least 8 counties in Colorado and over 1,000 locations worldwide.

Riebeckite is not really of any significant source of value, as this Iron- and Sodium-bearing mineral isn’t significantly useful as any kind of ore or an indication of any additional valuable minerals nearby, perhaps with the exception of Zircon and TItanite on occasion, but it’s a remarkable mineral and prized by Colorado collectors all the same!

If you just so happen to be out on a hike and see a mineral like this, now you may be able to recognize Riebeckite for yourself!