Lapis Lazuli

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Egyptian artwork: A winged scarab made of gold with lapis lazulli, malachite, turqoise and a carnelian sun inlay work.

Lapis lazuli is a rock aggregate made up from - predominantly - the minerals lazurite, sodalite, nosalite and hauyne. It has a typical cobalt blue color, often with patches of pyrite (golden) and/ or calcite (white). It was this rock which was powdered to create the ultramarine pigment used by painters prior to the 19th century[1]. Historically this gemstone comes from Afghanistan and this location was reported by Marco Polo as early as 1271, although the Romans already knew about and even the Bible[2] refers to this aggregate of such a wonderful color. Another famous locality where lapis lazuli is mined is in the Andes mountain range of Chile.

Lapis lazuli is often mimicked by a dyed jasper, but it does not show the white and golden patches. Sodalite, one of the components of lapis lazuli, is often mistaken for it, but the color is much paler. There is also a sintered synthetic spinel which imitates lapis lazuli.

Dyeing and impregnation occurs on lesser quality gems and these can be easily removed by acetone. Leaving these stones in the sun for a too long a period of time will cause the dye or impregnation to stain the environment.

Lapis lazuli ring 30-1-1925a.jpg
Gemological information for lapis lazuli
Color Cobalt blue with white or golden patches (calcite and pyrite)
Crystal Structure Rock
Refractive Index ~1.50
Durability Durable
Hardness 5.5
Treatments Dying, imitations
Country of origin Afghanistan, Chile, Russia

Notes

  1. Webster, 251
  2. Exodus 28:18

Sources consulted

  • Gemmology Third Edition - Peter G. Read
  • Gems, Their Sources, Descriptions and Identification 4th edition - Robert Webster, B.W. Anderson

Online G&G articles on lapis lazuli

Lang Antiques
Lang Antiques