Lapis Lazuli Description

Lapis Lazuli
Lapis lazuli is an aggregate of several minerals. Lazurite grains provide its characteristic blue color, while golden flakes of pyrite can add attractive contrast.
Lapis lazuli is a rock, which means it’s an aggregate of several minerals. This ancient gem contains three minerals in varying amounts: lazurite, calcite, and pyrite. Sometimes, it also contains one or more of the following: diopside, amphibole, feldspar, and mica.

Lapis Lazuli
Lapis lazuli is an aggregate of several minerals. Lazurite grains provide its characteristic color. The higher the percentage of lazurite grains in the aggregate, the darker the blue color. - John Koivula
Lapis frequently contains varying amounts of whitish calcite matrix—the host rock that surrounds the gem—or flecks or veins of glinting yellow pyrite, or both. The gem can also have a smoothly uniform bodycolor, free of visible pyrite and calcite.

Lapis Lazuli
Calcite shows up as white flecks or streaks in the aggregate.
Lapis Lazuli
The golden, metallic-looking spots in lapis are pyrite. - Robert Weldon, courtesy Gary Bowersox
Lapis is semitranslucent to opaque, with a waxy to vitreous luster. It has fair toughness, and its hardness ranges from 5 to 6 on the Mohs scale, depending on the mix of minerals.

Variously described as indigo, royal, midnight, or marine blue, lapis lazuli’s signature hue is slightly greenish blue to violetish blue, medium to dark in tone, and highly saturated. In its most-prized form, lapis lazuli has no visible calcite, although it might have gold-colored pyrite flecks. If the flecks are small and sprinkled attractively throughout the gem, their presence doesn’t necessarily lower lapis lazuli’s value. The lowest-quality lapis looks dull and green, the result of an excess of pyrite. Lapis with white calcite streaks is less valuable.

Lapis Lazuli
The calcite matrix in this cabochon will lower its appeal to most buyers. - Robert Weldon
Although many people associate lapis with dark blue, it’s also found in other shades of blue, and even other hues. Its color can range from deep violet blue and royal blue to light blue to turquoise blue to a greenish blue. The combination of different minerals in the aggregate determines the color. For example, lazurite is responsible for producing royal blue lapis, while a mineral called afghanite creates a pale blue shade.

Lapis Lazuli
This striking freeform carving displays a lovely shade of blue along with attractive golden pyrite accents. - Robert Weldon, courtesy Gary Bowersox
Worldwide, lapis is mined in several areas. The traditional source of the finest lapis lazuli is the same today as it was thousands of years ago—the mountains of Afghanistan. Other major sources are Chile and Lake Baikal in Siberia, Russia. Minor sources are Angola, Canada, Colorado (US), and Pakistan.

Lapis, lazuli
Afghanistan is the world’s major source of lapis lazuli as well as the major source of the gem’s best color. - Dr. Edward J. Gubelin