Lapis Lazuli - Composition and Color

Lapis lazuli is a blue metamorphic rock that has been used by people as a gemstone, sculpting material, and ornamental material for thousands of years.

The most important mineral component of lapis lazuli is lazurite (25% to 40%), a feldspathoid silicate mineral with the formula (Na,Ca)₈(AlSiO₄)₆(S,SO₄,Cl)_1-2. 

Most lapis lazuli also contains calcite (white), sodalite (blue), and pyrite (metallic yellow). Some samples of lapis lazuli contain augite; diopside; enstatite; mica; hauynite; hornblende, nosean, and sulfur-rich löllingite geyerite.

Polished Lapis lazuli. Photo:  New Moon Beginnings

Formation of Lapis Lazuli

Lapis lazuli is formed when limestone and other rocks are subjected to high temperatures and pressures. This process is called contact metamorphism. Lapis lazuli is typically found in contact metamorphic zones near igneous intrusions.

Lapis Lazuli Properties and Uses

Lazurite is a feldspathoid and a member of the sodalite group. Lazurite crystallizes in the isometric system although well formed crystals are rare. It is usually massive and forms the bulk of the gemstone lapis lazuli.

The intense blue color is due to the presence of the trisulfur radical anion (S₃^-) in the crystal.

Lapis takes an excellent polish and can be made into jewelry, carvings, boxes, mosaics, ornaments, small statues, and vases. During the Renaissance, lapis was ground and processed to make the pigment ultramarine for use in frescoes and oil painting. Its usage as a pigment in oil paint largely ended in the early 19th century when a chemically identical synthetic variety became available.

Rough lapis. Photo: Arsaa Gems And Minerals

High-quality lapis lazuli has been used as a mineral pigment for over 1,000 years. Bright blue pieces of lapis are trimmed of impurities and ground to a fine powder; the powder can then be mixed with oil or another vehicle for use as a paint.

Where is Lapis Lazuli Found?

Lapis lazuli was discovered around 6,000 years ago in the West Hindu-Kush Mountains of present-day Afghanistan. Today, Afghanistan continues to be the leading producer of the gem. Other countries involved in production include Angola, Argentina, Canada, Chile, India, Italy, Myanmar, Pakistan, the United States, and Russia.

Ultramarine Pigment

Ultramarine

Ultramarine is a deep blue color pigment which was originally made by grinding lapis lazuli into a powder. The name comes from the Latin ultramarinus, literally "beyond the sea", because the pigment was imported into Europe from mines in Afghanistan.

Metaphysical Properties of Lapis Lazuli

Lapis lazuli is often associated with wisdom, truth, and protection. It is said to promote clarity of thought and to help people to speak their truth. Lapis lazuli is also said to be a protective stone, and it is often used in meditation and other spiritual practices.