Quartz is one of the most abundant minerals in the Earth's crust. It is the major constituent of beach sand and an important component of many types of rocks. Quartz is composed of the elements silicon and oxygen. In its pure state it is colorless, but just small amounts of various impurity atoms can yield a variety of colors. It is common to find inclusions in quartz crystals. Quartz is usually one of the last minerals to form in a deposit, so it sometimes grows around existing crystals. Because quartz is commonly clear, the inclusions are easy to see. This 11.50ct quartz from Madagascar is a fancy cut square gem with inclusions of fluorite. These light violet blue inclusions are octahedral in shape, typical for fluorite as it forms in the cubic system.
