Geological Survey

“ Inexperienced buyers must take whatever steps are needed to ensure that gems they intend to purchase are exactly what the seller purports them to be and that they are being offered at a fair market price. ”

“ Each coral polyp, a tiny marine animal that lives in enormous colonies, extracts calcium carbonate from the sea and exudes it to build a protective home around and above itself. Each generation of polyps dies in its protective home and each succeeding generation builds on top of its predecessor. ”

“ Each environment tends to have a characteristic suite of gem materials, but many kinds of gems occur in more than one environment. Most gemstones are found in igneous rocks and alluvial gravels, but sedimentary and metamorphic rocks may also contain gem materials. ”

“ Gemstones: Value of U.S. production vs. imports, 1986 and 1989 [1]
[1] Estimated.
[2] Including freshwater pearls natural, and cultured.
[3] Imports - exports + adjustments for Government and industry stock changes. Source: Mineral Commodity Summaries, 1991, U.S. Bureau of Mines. U.S. production of commercial gems includes agate, beryl, freshwater pearl, garnet, jade, jasper, mother-of-pearl, opal, peridot, quartz, sapphire, tourmaline, and turquoise.
Except for the few gem diamonds found each year in Arkansas, U.S. diamond production is very low. ”

“ Check the phone book for your nearest rock and mineral shop and talk to the owners.
Role of the U.S. Geological Survey (USGS)
The USGS reports deposits that seem likely to contain gemstones. It is not a function of the USGS to exploit such resources.
USGS geologists perform continuing research on kimberlites, the initial source of diamonds. Not all kimberlites are diamond-bearing, and some of the research is directed to learning what indications you look for during exploration to distinguish fertile from barren kimberlite. ”

“ However, the flow of money into the local economy by paying these small fees and by the purchase of gemstones is minor compared to the money the enthusiasts spend for lodging and other living expenses while visiting an area to dig for gemstones. ”

“ Aquamarine, Brazil.
5 Mineral gemstones
Hardness and specific gravity are two of the major characteristics of gemstones.
Hardness of a gemstone is its resistance to scratching and may be described relative to a standard scale of 10 minerals known as the Mohs scale. F. Mohs, an Austrian mineralogist, developed this scale in 1822.
According to Mohs’ scale, the hardness of—
Specific gravity is the number of times heavier a gemstone of any volume is than an equal volume of water ”

“ Chrysoprase. Moss agate. Plasma. Prase. Sard. Jasper.
Spinel (hardness: 8 Mohs)
Magnesium aluminum oxide
Specific gravity: 3.58-4.06
7
Balas ruby: Red
Almandine spinel: Purple red
Rubicelle: Orange
Sapphire spinel and ghanospinel: Blue
Chlorspinel: Green
Candelabra: white quartz, blue-capped red elbaite, and tan albite, California.
Topaz (hardness: 8 Mohs)
Aluminum silicate fluoride hydroxide
Specific gravity: 3.5-3.6
Wine yellow, pale blue, green, violet, or red
Tourmaline (hardness: 7-7.5 Mohs)
Complex aluminum borosilicate (Elbaite, Dravite, Uvite)
Specific gravity: 3.03-3.25 ”