Gem minerals are minerals that are used to make jewelry and other decorative items. Two examples of gem minerals are BERYL and TURQUOISE. BERYL is a mineral composed of beryllium aluminum cyclosilicate, and is usually found in shades of green, blue, yellow, pink, and white. TURQUOISE is an opaque, blue-to-green mineral that is composed of hydrated copper and aluminum phosphate. It is often used in jewelry and other decorative items.