Benitoite from San Benito County - J. Veevaert



Superb specimen of benitoite with large gemmy and lustrous crystals up to 2.3 cm across on a matrix of natrolite. Dr. H. Holmesspecimen J.Veevaert photograph. Benitoite by John Veevaert All photographs and content are copyrighted by theauthor. December 5, 1997 They may not be used without permission.... Just ask:)


Introduction

 Of all the minerals that exist few have has a distinguished aplace in the world of mineralogy as benitoite (pronounced "ben-ee-toe-ite").Benitoite (see the first two pictures!), named after San Benito County,California where it was discovered in 1907, is a prized gemstone of extremerarity. When first discovered it was initially thought to be sapphire. Soon, after careful analysis, it was found to be a new mineral by Dr. GeorgeLouderback, who received several samples at the University of California,Berkeley for identification. He recognized that it was not sapphire and began the process of describing it along with a what he thought were alsonew minerals that occurred with the benitoite which he named carlosite and joaquinite (It turns out later that carlosite was really neptunite previously described from Greenland and the Ural Mountains in Russia. Evenso, specimens of neptunite from the Gem Mine were far superior to any other known occurrence for the species. Joaquinite was, in fact, a new mineral).

Benitoite in gem quality, occurs only in San Benito County. It has been found in several locales in the vicinity of the Dallas, or "Benitoite",Gem Mine (see figure 2) as it has become to be known. But only the Benitoite Gem Mine has produced gem quality benitoite in substantial quantity. TheJunnila Mine located about 10 km to the west of the Gem Mine also has produced some gem benitoite but it is a very small amount. Benitoite has also been found in locations else where in Japan and Arkansas (Henry Barwood, personal communication, 1997). Earlier reports of the mineral being found as grainsin Texas and Belgium were misreported as benitoite. Bentonite, and not benitoite, was the mineral identified at those locations (Henry Barwood,personal communication, 1997). Owing to the fact that gem quality benitoiteis restricted to California only it was recognized by the California State Legislature as the Official State Gemstone on October 1, 1985. Figure 2.


Composite view of the Benitoite Gem Mine as it lookedin 1990.

Today, Benitoite is in very high demand for both gemstones and as specimens. People all over the world are discovering the vast array of valuable colored gemstones and how exciting and exotic they can be in contrast to rather abundant minerals like diamonds. In terms of scarcity gem quality benitoite is probably on the same level as gem red beryl and a few other rare stones like Alexandrite. In contrast, diamonds, rubies, emeralds, tanzanites andother pricey gemstones are orders of magnitude more abundant than benitoite. Benitoite is a true rarity among gemstone collectors and the availability of quality stones will likely never be high as the original deposit has been completely worked out. There is a possibility that the Junnila mine may have some reserves of gem benitoite but the deposit is rather small and the vast majority of the benitoite at that locale is very low grade.In all probability, what exists today is probably all that there ever willbe with only a very minor amount of new material to be expected from there working of the old Gem Mine tailings and coluvium.

I know from personal experience that it is difficult to obtain high quality benitoite specimens and gem rough. All of the shows that I attend rarely have good benitoite specimens available and when they are they comewith ~the~ price tag to reflect the scarcity. Unlike the stock market,the future of high quality benitoite specimens and gemstones will likely forever be on an upward trend.    
Article from : Trinity Minerals