Quartz specimens with mineral inclusions are very common make attractive gemstones. Rutilated quartz or "sagenite", popularly known to as Venus-hair stone, is quartz with needle-like rutile crystals. These may be red, black or brassy yellow and have a metallic lustre.
Tourmalinated quartz has inclusions of black tourmaline, which form prismatic or needle like crystals. Opaque, metallic yellow inclusions of gold are found in specimens of "gold quartz". Inclusions of silver may also be found within quartz, often in branch like dendrites, and are silvery grey or black, opaque and metallic. The iron minerals, goethite and pyrite, are also found as inclusions. If cut in cabochon, quartz containing goethite may show the cat's eye effect.
Quartz with inclusions is found in Madagascar, Brazil, South Africa, India, Sri Lanka, Germany and Switzerland.
Sagenitic Quartz Pictures