[[Image:Feldspar.gif|thumb|300px]]Of all of the minerals in the Earth's crust, the aluminosilicate, '''feldspar''', is the most common. It is a very useful industrial [[mineral]] that finds applications in making [[glass]], plumbing fixtures, tile and pottery. These uses in the United States accounted for about 630,000 ton of U.S. produced feldspar valued at about $27.4 million. It is also a [[gemstone]].<ref>http://minerals.usgs.gov/minerals/pubs/commodity/gemstones/sp14-95/feldspar.html</ref>Feldspar is number 6 on the [[Mohs Hardness Scale]].
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