This is one to keep you entertained when there is nothing on television! Matrix is massive translucent Calcite. This is topped by hollow rectangular blades made of sharp and undamaged little dog-tooth Calcite crystals. Partially embedded in the Calcites are about a dozen balls of iridescent Pyrite, biggest to about 1.5 cm. From the San Antonio Mine, East Camp, Santa Eulalia District, Mun. de Aquiles Serdán, Chihuahua.