Precious gemstone cerussite is an admired collector’s stone, also known as lead spar. The name cerussite is from the Latin, cerussa, meaning “white lead.” Coming from the class of carbonates, cerusiite is composed from lead carbonate. The crystal system is orthorhombic and its habit is tabular, equant, bipyramidal, also “snowflake” twins. There are, however, a number of color variations as the result of inclusions. For example, black and gray crystals contain inclusions of galena (lead sulfide), and green crystals derive their color from malachite. Chrome precious gemstone cerussite contains the element chromium and is bright yellow. It is the most plentiful secondary lead mineral at Tsumeb mines in Namibia. Precious gemstone cerussite is colorless or white, but sometimes there is also available in gray, yellow, blue-green, and black.
With 1.804-2.078 refractive index and a 0.274 birefringence, precious gemstone cerussite is a popular mineral, known for its high density and excellent sparkle. Precious gemstone cerussite twins are an essential gem for collectors of twinned crystals. Its softness makes it inappropriate for use as a gemstone, but it is frequently faceted in a brilliant cut for collectors. Precious gemstone cerussite as one of unique natural gemstones, has distinct-in-two-directions cleavage. The best transparent and colorless crystals have come from Tsumeb in Namibia, and here, excellent, clear, twinned crystals have been found up to 23 inches (60 cm) in length. Most crystals are twinned but a few untwinned specimens are seen from time to time. The largest cut precious gemstone cerussite weighs about 900 carats and is at the Royal Ontario Museum in Toronto, Canada. The luster is adamantine to waxy and has a conchoidal fracture.
Precious gemstone cerussite is a lead carbonate mineral, and it is usually found in the oxidized zones of lead ore deposits with 0.055 dispersion and the specific gravity is between 6.46-6.57. It is transparent to opaque and very brittle. Precious gemstone cerussite is formed by the action of carbonate and bicarbonate solutions on galena (a lustrous, blue-gray, lead-ore mineral). The hardness is at the level 3.5. Precious gemstone cerussite has been known to form some intricate geometrical constructions and interesting star shapes as a result of the multiple twinning that occurs in its crystal structure. It is an important ore of lead, and it is widely distributed throughout the world. Its high luster is mainly the result of its high lead content. For a transparent mineral, precious gemstone cerussite is extremely and unusually dense. The main sources are in Namibia (Tsumeb), USA (Utah, Arizona, New Mexico), Germany, Australia, Morocco, Congo, and Tasmania.
