Lapis Lazuli

Hardness: 5-5.5 on Mohs scale. Color: Intense azure blue to violet-blue, often with white calcite and metallic gold pyrite inclusions. Luster: Dull to greasy. Crystal structure: Typically massive, granular, or compact, rarely dodecahedral crystals. Cleavage: Indistinct. Specific Gravity: 2.7-2.9.

Formed through contact metamorphism in crystalline limestone, typically in regions with high temperatures and pressures. It forms when limestone or marble is altered by the intrusion of igneous rock, causing the formation of new minerals. Its geological age varies depending on the deposit, but many significant deposits are hundreds of millions of years old.

Primarily used as a gemstone in jewelry (cabochons, beads, carvings). Also used for ornamental objects, inlays, and sculptures. Historically, it was a crucial source for the pigment ultramarine, used in paintings. In modern times, it's sometimes used for decorative architectural elements.

Lapis Lazuli has been valued since antiquity for its intense blue color. It was used in ancient Egypt for jewelry and ornate objects, and Roman scholars described it as 'a starry firmament'. In the Middle Ages, it was ground into a powder to create ultramarine, the finest and most expensive blue pigment used by Renaissance painters (e.g., in masterpieces by Michelangelo and Vermeer). It has also been used for philosophical and spiritual purposes, being associated with wisdom, truth, and royalty.

To identify Lapis Lazuli in the field, look for its distinctive deep blue color, often flecked with golden (pyrite) and white (calcite) inclusions. It is opaque. A scratch test (Mohs hardness of 5-5.5) can help distinguish it from softer lookalikes. It's commonly found in Afghanistan (historically the highest quality), Russia (Lake Baikal), Chile (Ovalle), Myanmar (Burma), Pakistan, Canada, and the United States (California, Colorado). For collectors, the presence of distinct pyrite specks and minimal calcite generally indicates higher quality. It often fluoresces a dull reddish or orangish glow under long-wave UV light, which can be a helpful identification tool.