What is the Difference Between Lazurite and Lapis Lazuli?

Lazurite and lapis lazuli are two similar-sounding minerals that are often confused with each other. However, there are some key differences between these two blue rocks.

Lazurite

Lazurite is a mineral primarily composed of lazurite crystals. It is a feldspathoid silicate mineral that contains sulfur and is a member of the sodalite group. Lazurite typically has an intense blue color and forms in crystalline masses or grains. It has a hardness of 5 to 5.5 on the Mohs hardness scale.

Lazurite is an important rock-forming mineral and is found in many metamorphic and igneous rocks worldwide. Major deposits of lazurite have been found in Afghanistan, Russia, Chile, Italy, Canada, and the United States. In its pure mineral form, lazurite is referred to as “ultramarine”, which comes from the Latin “ultramarinus”, meaning “beyond the sea”. This refers to the blue color being more intense than the sea.

The intense blue color of lazurite gems led to its use as a pigment for paintings and dyes dating back to the 6th century. The vibrant blue lazurite pigment was more expensive than gold at the time. While synthetic versions have largely replaced naturally-derived lazurite pigments today, it is still valued as a gemstone. Lazurite is often cut into cabochons, beads, or used for ornamental carvings.

Lapis Lazuli

In comparison, lapis lazuli is a rock primarily composed of multiple minerals, with lazurite being the main component. Lazurite makes up about 25% to 40% of lapis lazuli. The other major minerals that comprise lapis lazuli are calcite, pyrite, and white mica.

Trace amounts of other minerals can also be present. The combination of minerals gives lapis lazuli its distinct blue color with sparkling flecks of pyrite. While both lazurite and lapis lazuli contain the vibrant blue lazurite crystals, lapis lazuli’s color can vary from dark blue to pale blue with white marbling depending on the mineral composition.

Lapis lazuli rates between 5 to 6 on the Mohs hardness scale due to the softer minerals mixed with the lazurite. It has been prized as a gemstone for thousands of years, often referred to as the “stone of royalty”. Ancient Egyptians used lapis lazuli extensively in jewelry and ornamental objects.

Like lazurite, the blue color came from the molecular structure of the lazurite crystals. The flecks of pyrite in lapis lazuli give it a glittery, starry appearance. Lapis lazuli cabochons were popular in Roman times and still used in jewelry today. The most valuable lapis lazuli has a deep blue color with few white calcite veins.

While lazurite and lapis lazuli share the vibrant blue lazurite crystals, lazurite is a pure mineral while lapis lazuli is a rock composed of several minerals. The lazurite content and mix of minerals account for the differences between these two blue stones. Both have a long history as prized materials for art, ornamental objects, and jewelry due to their intense blue colors.