This pack of 12 raw quartz specimens are an authentic example of mineral rock suitable for geology education and identification exercises. QUARTZ | One of the most abundant minerals on Earth. The tightly packed framework of silica tetrahedral that makes up this mineral gives it a high hardness of 7, a lack of cleavage planes, and a distinct euhedral crystal habit. Each specimen measures approximately 1" and has been selected and hand-processed by a geologist to ensure it exhibits defining characteristics. Specimens are individually packaged in a transparent bag, labeled and barcoded for easy identification and storage.