Lapis Lazuli

Mohs hardness: 5-5.5. Color: Often deep azure blue to violet-blue, but can also be greenish-blue. Luster: Dull to greasy. Crystal Structure: Isometric, typically found in massive, granular, or compact forms. Cleavage: Indistinct. Specific Gravity: 2.7-2.9.

Lapis Lazuli is a metamorphic rock formed by contact metamorphism of limestone or marble. It forms when limestone, rich in calcium, is intruded by igneous rocks, leading to reactions between the limestone and sulfur-rich solutions or gases. This process occurs under high temperatures and pressures, typically in mountainous regions. Its geological age varies, with deposits spanning from Proterozoic to Cenozoic eras.

Predominantly used for ornamental purposes, jewelry (cabochons, beads, carvings), and small sculptures. Historically, it was ground to create the highly valued blue pigment, ultramarine, used in paintings. It is also used as a decorative stone in architecture and interior design.

Lapis Lazuli has been prized since antiquity for its intense blue color. It was used extensively by ancient civilizations such as the Egyptians, Mesopotamians, and Romans for jewelry, carvings, and ornamental objects. The pigment ultramarine, highly valued by Renaissance painters, was originally made by grinding lapis lazuli. The golden flecks in lapis lazuli are due to pyrite inclusions, and white streaks are typically calcite. It's often associated with royalty and divinity.

When identifying in the field, look for its distinctive deep blue color, often with golden (pyrite) specks and white (calcite) streaks. It will not scratch glass easily. It's commonly found in metamorphic environments, particularly where limestone has undergone metamorphism. Major sources include Afghanistan (Badakhshan province), Russia (Lake Baikal region), Chile (Ovalle), and smaller deposits in the United States (Colorado), Myanmar, and Pakistan. For collectors, look for vibrant blue color with good distribution of pyrite and minimal calcite streaks for higher value.