California-Sourced Precious Stones: Benitoite Gemstones
In the heart of San Benito County, California, a gemstone of extraordinary rarity and beauty was discovered in 1907. This gemstone, known as Benitoite, has since captivated the world with its mesmerising colours and fascinating origins.
Benitoite, a barium titanium silicate (BaTiSi3O9), forms in the trigonal portion of the hexagonal crystal system. It is a unique mineral, with outlets for its existence being limited to less than ten known locations worldwide. Excluding California, only three of these locations are found in Japan, Australia, and Arkansas, USA.
Benitoite showcases a beautiful range of colours, from blue to slightly purplish-blue, or white to colourless, with very few stones being naturally pink. It was initially mistaken for blue diamonds by its discoverer, James Marshall Couch, due to its striking blue hue. However, further investigation revealed it to be a new mineral, distinct from spinel or sapphire.
The gemstone's origins are closely tied to the unique metamorphic conditions found in California's blueschist terranes, particularly in the San Benito River area. Benitoite is solely found in the hydrothermally altered zones of the blueschist, and it forms where the veins narrow or terminate, usually coated by natrolite.
The Benitoite Gem Mine, which operated from 1907 to 2005 under several different names and owners, was the only one to produce faceted material in commercial quantity. The common form that benitoite crystalizes in is a ditrigonal-dipyramidal habit, the most complex form of a trigonal crystal.
Gemstones are typically very small due to the flat habit of the crystals, with strong colour zoning and inclusions of amphibole and pyroxene. Most stones are not treated in any way, but an orange colour can be caused in some stones through heat treatment. Cut stones are typically smaller than one carat, but many stones larger than 4ct have been produced over the years with the largest cut benitoite weighing in at 15.42ct.
Benitoite's discovery holds an incredible story of its discovery by a humble melon farmer turned prospector. Its name was officially given on July 30, 1907, by Associate Professor of Geology at the University of California, Berkley, Davis Louderback. Leland Barnes Hawkins, Sr., a mine engineer and friend, was asked to determine the value of the rough crystals.
Despite its scarcity, Benitoite continues to captivate collectors and jewellery enthusiasts alike. Its deep colour, higher dispersion than a diamond, and the flat habit of its crystals contribute to its allure. As the official state gemstone of California, Benitoite stands as a testament to the state's rich geological history and the beauty that lies hidden beneath its surface.
- The foundation of gemmology as a science took an interesting turn with the discovery of Benitoite in 1907, a unique mineral that initially was mistaken for blue diamonds.
- To delve deeper into the world of Benitoite, one can consider enrolling in courses offered by accredited gemmology foundations, providing a diploma that certifies expertise in the field.
- With its scarcity and deeper colors, Benitoite has become an attractive investment for finance-savvy businesspersons looking to venture into the gemstone market.
- The journey of Benitoite, from its discovery in San Benito County, California, to its recognition as the official state gemstone, offers an intriguing case study in the relationship between science, business, and the value of natural resources.
