Lapis Lazuli

Hardness: 5-5.5 on Mohs scale. Color: Intense azure blue to violet blue, often with golden specks (pyrite) and white streaks (calcite). Luster: Dull to greasy. Crystal Structure: Typically massive, granular, or compact aggregate; individual crystals of lazurite are isometric but rare to find. Cleavage: Indistinct in lazurite. Specific Gravity: 2.7-2.9.

Lapis Lazuli is a metamorphic rock formed by contact metamorphism of limestone with igneous intrusions. This process involves the alteration of calcium-rich sedimentary rocks under high temperature and pressure, leading to the formation of specific minerals like lazurite. It typically forms in marble, usually in dolomitic limestone. The geological age of prominent deposits can range from Precambrian to Tertiary.

Historically, Lapis Lazuli is most famous for its use as a pigment (ultramarine) in paints, particularly during the Renaissance. It's widely used in jewelry (beads, cabochons, carvings) and ornamental objects such as sculptures, vases, and inlays. Its beautiful blue color makes it highly prized.

Lapis Lazuli has been valued since antiquity for its intense blue color. Ancient Egyptians used it for jewelry, amulets, and powdered cosmetics. The funeral mask of Tutankhamun is decorated with lapis lazuli. The most famous source of lapis lazuli for thousands of years has been the Sar-e-Sang mine in Afghanistan. It was also believed to possess healing properties and was ground into powder and mixed with honey to create a medicinal paste.

In the field, Lapis Lazuli is identified by its distinctive deep blue color, often with characteristic golden pyrite flecks and white calcite veins. Its relative softness (scratchable with a knife) and lack of well-formed crystals are also key indicators. The scratch test can confirm its hardness. It can be confused with Sodalite (which usually lacks pyrite and has a less intense blue) or Dumortierite (often fibrous, different luster). Major sources include Afghanistan (Badakhshan province), Russia (Lake Baikal region), and Chile (Ovalle). For collectors, look for specimens with a vibrant, even blue color and well-distributed pyrite inclusions; excessive white calcite reduces its value.