3.2" Ankerite Crystals with Sphalerite and Pyrite - Colorado

This specimen contains pearly ankerite crystals, covered by a light brown mineral coating. Small lustrous, double-sided sphalerite crystals can be found around the entire specimen as well, breaking free between the rhombohedral ankerite crystals. When looking closer, while fewer in numbers, pyrite cubes can be found scattered throughout the specimen as well.

Ankerite is a Mg rich minerals with a chemical formula of Ca(Fe2+,Mg)(CO3)2. As a mineral of the Dolomite Group, ankerite typically forms a crystal structure similar to that of rhombohedral calcite. The crystals often have a pearly white luster, to sometimes a light yellow-brown coating, depending on iron content. Other minerals, such as pyrite, sphalerite, and quartz are just a few of the known crystals to form in association with ankerite.
Ankerite, Spahlerite & Pyrite
Eagle Mine, Gilman, Colorado
3.2" long, 2.05" wide