Sunday, August 28, 2011

Lapis Lazuli - The Perfect Blue !

Lapis Lazuli is a relatively rare semi-precious stone that has been prized since antiquity for its intense blue color. Lapis Lazuli is a gemstone of the kind that might have come straight out of the Arabian Nights: a deep blue with golden inclusions of pyrites which shimmer like little stars.

Lapis Lazuli has been collected from mines in the Badakhshan province of Afghanistan for over 6,000 years and there are sources that are found as far east as in the region around Lake Baikal in Siberia. Trade in the stone is ancient enough for Lapis jewelry to have been found at Predynastic Egyptian and ancient Sumerian sites, and as Lapis beads at neolithic burials in Mehrgarh, the Caucasus, and even as far from Afghanistan as Mauritania

The main component of Lapis Lazuli is Lazurite (25% to 40%), a feldspathoid silicate mineral. Most Lapis Lazuli also contains Calcite (white), Sodalite (blue), and Pyrite (metallic yellow). Other possible constituentsare: augite; diopside; enstatite; mica; hauynite; hornblende, and nosean. Some Lapis Lazuli contains trace amounts of the sulfur-rich löllingite variety geyerite. Lapis Lazuli usually occurs in crystalline marble as a result of contact metamorphism.

As mentioned Lapis Lazuli has been primarily found in limestone in the Kokcha River valley of the Badakhshan province in northeastern Afghanistan, where the Sar-e-Sang mine deposits have been worked for more than 6,000 years. In addition to the Afghan deposits, Lapis has been extracted for many years in the Andes (near Ovalle, Chile), the Lake Baikal region of Russia; Siberia; Angola; Burma; Pakistan; Canada; India; and in the USA in California and Colorado. Not all Lapis is of gemstone quality, but that which is can produce beautiful jewelry. Most Lapis is prepared in cabochon shapes.

Before the year 1834, when it became possible to produce this blue color synthetically, the only ultramarine available was that valuable substance made from genuine Lapis Lazuli that shines out at us from many works of art today. Many pictures of the Madonna, for example, were created using this paint. But in those days, ultramarine blue was not only precious and so intense that its radiance outshone all other colors; it was also very expensive. But unlike all other blue pigments, which tend to pale in the light, it has lost none of its radiance to this very day. Nowadays, the blue pigment obtained from Lapis Lazuli is mainly used in restoration work and by collectors of historical paints. Since Afghanistan is the primary supplier of gem quality material, current world conditions on top of the very extreme remoteness of the mines, Lapis Lazuli has become harder to obtain and the price has risen accordingly. However, Lapis jewelry is still in high demand because of its beauty.

Lapis Lazuli mounted in a Silver Pendant and a Silver Ring

In recent years Lapis Lazuli is commercially "synthesized" (actually simulated) by the Gilson process, using artificial ultramarine and hydrous zinc phosphates. Some dealers try and substitute Lapis using Spinel or Sodalite, or by dyed Jasper or by our old friend the Turquoise substitute, Howlite.