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Location of the Benitoite Deposit
The benitoite mine is in the southeastern part of San Benito County, near the Fresno County line. The deposit is about 35 miles by road northwest of Coalinga in the Diablo Range, about three-fourths of a mile south of Santa Rita Peak, and on one of the tributaries of San Benito River. The elevation of…
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Who Discovered Benitoite?
The difficulty mentioned by Doctor Louderback in learning who was the original discoverer of the benitoite property was encountered by the writer. It is evident that J. M. Couch, of Coalinga, grubstaked by R. W. Dallas, was instrumental in finding the deposit. Whether he discovered it while out alone or on a second trip with…
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Report on the Discovery of Benitoite by Douglas B. Sterrett (1911)
The information below is a verbatim transcript of an article about the discovery, geology, mining and properties of benitoite, by Douglas B. Sterrett. It was published in the 1909 edition of Mineral Resources of the United States, by the United States Geological Survey. [2] Description of Benitoite An excellent description of the new California gem mineral,…
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Physical Properties of Benitoite
Benitoite has an appearance that is very similar to sapphire. Its blue color and pleochroism are very much like sapphire’s. Benitoite and sapphire have overlapping refractive indices, but benitoite has a much higher birefringence, which often shows birefringence blink. Sapphire has a Mohs hardness of 9, while benitoite is much softer at 6 to 6.5. Benitoite has a…
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What Is Benitoite?
Benitoite is an extremely rare mineral that is best known for being the official state gemstone of California. It is a barium titanium silicate mineral, usually blue in color, that is found in rocks that have been altered by hydrothermal metamorphism. Its chemical composition is BaTi(Si3O9). Benitoite’s identification and original description was based upon specimens found in the headwaters of…
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Global Copper Resource Assessment
The USGS assessed undiscovered copper in two deposit types that account for about 80 percent of the world’s copper supply. Porphyry copper deposits account for about 60 percent of the world’s copper. In porphyry copper deposits, copper ore minerals are disseminated in igneous intrusions. Sediment-hosted stratabound copper deposits, in which copper is concentrated in layers…
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How Do We Ensure Adequate Supplies of Copper for the Future?
To help predict where future copper resources might be located, USGS scientists study how and where known copper resources are concentrated in the Earth’s crust and use that knowledge to assess the potential for undiscovered copper resources. Techniques to assess mineral resource potential have been developed and refined by the USGS to support the stewardship…
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Copper Supply, Demand and Recycling
The world’s production (supply) and consumption (demand) of copper have increased dramatically in the past 25 years. As large developing countries have entered the global market, demand for mineral commodities, including copper, has increased. In the past 20 years, the Andean region of South America has emerged as the world’s most productive copper region. In…
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Types of Copper Deposits
Copper occurs in many forms, but the circumstances that control how, when, and where it is deposited are highly variable. As a result, copper occurs in many different minerals. Chalcopyrite is the most abundant and economically significant of the copper minerals. Research designed to better understand the geologic processes that produce mineral deposits, including copper deposits, is an…
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What Properties Make Copper Useful?
The excellent alloying properties of copper have made it invaluable when combined with other metals, such as zinc (to form brass), tin (to form bronze), or nickel. These alloys have desirable characteristics and, depending on their composition, are developed for highly specialized applications. For example, copper-nickel alloy is applied to the hulls of ships because it does not corrode…