Lapis Lazuli

Lapis Lazuli (often shortened to 'lapis') is a deep-blue metamorphic rock used as a semi-precious stone that has been prized since antiquity for its intense color. Unlike most gemstones, it is a rock composed of multiple minerals, primarily lazurite (which gives the blue color), calcite (white veins), and pyrite (gold-colored flecks). The finest specimens are a uniform, intense royal blue.

Formation & Geology

Lapis forms through contact metamorphism, typically when limestone or marble is altered by hydrothermal processes. It is found in some localized, ancient deposits, most famously in the Sar-i Sang mines of Afghanistan, which have been worked for over 6,000 years. These mines provided the lapis used by the ancient Egyptians and Sumerians.

Physical Characteristics

Lapis has a hardness of 5 to 5.5, making it relatively soft and susceptible to scratching. It has a dull to vitreous luster and a blue streak. The presence of 'gold' pyrite flecks is considered a hallmark of genuine lapis, although too much white calcite can lower its value. It is porous and can be damaged by acids or harsh chemicals.

Historical Significance

Lapis Lazuli has one of the longest histories of any gemstone. It was used in the funeral mask of Tutankhamun and in the jewelry of Ur. During the Renaissance, it was ground into 'ultramarine', the most expensive and prized of all blue pigments, used by artists like Michelangelo and Vermeer to paint the robes of royalty and religious figures. Since 1881, the synthetic version of ultramarine has replaced it in most commercial paints.