Chemistry of Lapis Lazuli: A Difficult and Rare Gem

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Artists prized lapis lazuli as a welcome replacement for toxic compounds such as mercury and lead. Image by Palladian

The striking blue color of the mineral Lapis lazuli beckons to the discriminating eye, but the chemical beauty of this mineral is even more entrancing.

The semi-precious gem, once associated with royalty and eternity, gives an impression of other-worldly origins.

Its blue color has been sought by artist and alchemist alike. However, Lapis’ mineral veins occur in only a handful of regions of the world.

Where Does Lapis Lazuli Come From?

In one part of the world, the Sar-e Sang region of Afghanistan, mineral veins occur adjacently to regions of the rarest chemical elements.

The desired metals, such as uranium, tellurium, and erbium occur near the Lapis deposits of Afghanistan, as you can see in the map below – use the key at the left.

Ironically, the rare deposits may have played a role in how Lapis came to be in Afghanistan.

Lapis: Blue Mineral for Ancient Artists

The subtle blue tones of the Lapis mineral intrigued ancient artists. Artists could not readily reproduce any shades of blue. Early and unfortunate attempts to create blue led to loss of sanity from mercury and lead poisoning. Although the first use and discovery of Lapis remains hidden, the remnants of its use are found in ancient near-East and Asia.

Present day-scholars argue over the origins and uses of Lapis-laden artifacts. Although true Lapis maybe distinguished from imitation through instrumental analysis, what becomes apparent is the gem was used by shaman and the affluent alike.

The occurrence of Lapis mineral veins dot the Earth; this rare mineral varies from site to site. The molecular complexity of Lapis assures that the substance is not recreated exactly at different mining sites.

This is the color key to identifying minerals in the below spectral map of Afghanistan. Image courtesy of USGS.

What Makes Lapis Complex?

The complex nature of the molecule is due in part to its chemical formation. The general chemical make-up of the gem consists of the following elements: sodium, calcium, aluminum, silicon, oxygen and sulfur.

Lapis owes its blue coloring in part to the sulfur that embedded within the crystalline structure.

Lapis, Chemistry of the Past?

At the Sar-e Sang site in Afghanistan, the mineral occurs within granite formations.

In that part of the World, three distinct geologic time frames come together. The mineral sits beneath the Himalayan plateau where Asia, India and Eurasia meet. There are thus three different sources for the unique chemistry of Lapis to develop.

The Sar-e Sang mineral deposits sit in a geologically, ‘archeal’ part of the world.

This map shows a spectral image of mineral deposits. Image courtesy of USGS.

The archeal geology resembles the early Earth geochemistry; there was no discernible life, nor peat-like carbon. The three different sources of geology provided a unique cauldron of chemical ingredients to produce retro-Earth chemistry.

Prior to the present geologic era, the early-Earth was in a reduced atmospheric state where oxygen was scarce and sulfur-hydrogen loving bacteria were present.

The present-day carbon-oxygen cycles did not exist. Whatever ecological cycles were present, we are hard pressed to reproduce them. (While it is unknown whether sulfurous bacteria arose as a result of Lapis-type chemistry, the origins of geo-biochemistry are not completely ruled out.)

Lapis, Rare Find that is Difficult to Reproduce

The rare beauty that is Lapis is an experience to behold in the present world. Both artists and alchemists can attest to the difficulty with which Lapis may be reproduced or synthesized. Modern science has not gained an adequate foothold of its characterization either… But anyone can appreciate the beauty of lapis lazuli.

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