Description | This specimen contains red almandine,whitish-gray feldspar and white quartz. Almandine is iron-aluminum garnet, having ideal composition Fe3Al2Si3O12. It may contain magnesium, manganese or calcium as significant impurities. Like all garnets, almandine forms dodechahedral (12 sided) crystals whith each face having a rhombohedral shape. This sample is about 11 cm across. The white on the lower left is paint used to label the specimen. |