Porphyritic granite sample approximately 1" (3cm) in size Large crystals in a variety of shapes and colors make this felsic plutonic rock ideal for lessons in mineral identification and bulk rock chemistry Perfect size for use in classroom identification labs and exercises, correlates well to Next Generation Science Standards Evidence Statements Great for comparing cooling rates between samples with differently-sized crystals Specimen comes in clear labeled and barcoded bag for ideal storage Granite forms slowly in shallow or evolved magma chambers, and is also commonly found as magmatic intrusions in the crust. The large crystals are indicative of a slow cooling rate, and make mineral identification simple. Granite is a classic igneous rock, and is a must-have sample when discussing rock types, the rock cycle, and the formation, classification, and identification of igneous rocks. This sample is also available in packs of 12.