Frequently Asked Questions


The USGS studies geologic processes that concentrate mineral resources in the Earth's crust, and assesses areas of undiscovered mineral resources. We also collect national and international information on mineral commodities.

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Front page of USGS topographic maps symbol sheet
Like topographic maps, topographic map symbols have evolved over time. There is no single document that describes all the symbols used on all USGS topographic maps.   Topographic Map Symbols – Covers symbols on maps published 1947-2009. Most of these symbols are still in use. US Topo maps published 2013-present (PDF format only) have a topographic...
Ray Copper Mine
After 85 years of service, the U.S. Bureau of Mines (USBM) closed in 1996. Certain functions, such as the collection, analysis, and dissemination of minerals information, have been returned to the U.S. Geological Survey. For information on former USBM programs or publications, please see the following sources: The National Technical Reports...
mineral fact sheets
For statistical information about mineral commodities, visit the USGS Commodity Statistics and Information website. For locations outside the United States, the USGS International Minerals Statistics and Information website is the best starting point. 
Image: Rare Platinum Nugget
White gold was originally developed to imitate platinum (a naturally white metal). White gold is usually an alloy containing about 75% gold and about 25% nickel and zinc. If stamped 18 karat, it would be 75% pure gold.
Image: Russian Crown Jewels from the USGS Library
The fineness of jewelry gold is stated as the number of parts in twenty-four that are gold. Thus, 24 karat gold is pure gold; 12 K would be an alloy that is half gold and half copper or other metals.
Image: Celestite
A mineral is a naturally occurring inorganic element or compound having an orderly internal structure and characteristic chemical composition, crystal form, and physical properties. Common minerals include quartz, feldspar, mica, amphibole, olivine, and calcite. A rock is an aggregate of one or more minerals, or a body of undifferentiated mineral...
Silver metal specimen with pen for scale
Sterling silver is the standard of quality for articles containing 92.5% silver and 7.5% copper (and/or other alloys).
Close up of Chalcopyrite
Fool's Gold can be one of three minerals. The most common mineral mistaken for gold is pyrite. Chalcopyrite may also appear gold-like, and weathered mica can mimic gold as well. Compared to actual gold, these minerals will flake, powder or crumble when poked with a metal point, whereas gold will gouge or indent like soft lead. In addition, actual...
Image: Supergene Leached Zone at Silver Bell Mine
Of the 1,740,000 metric tons of silver discovered to date, 55% is found in just four countries on earth. All the silver discovered thus far would fit in a cube 55 meters on a side. Learn more at the USGS commodity website for silver.  
Image shows black pans with gold grains
About 244,000 metric tons of gold has been discovered to date (187,000 metric tons historically produced plus current underground reserves of 57,000 metric tons). Most of that gold has come from just three countries: China, Australia, and South Africa. The United States ranked fourth in gold production in 2016. All of the gold discovered thus far...
To date, roughly 700 million metric tons of copper have been produced around the world. This would fit into a cube measuring about 430 meters on a side. Identified deposits contain an estimated 2.1 billion metric tons of additional copper, which brings the total amount of discovered copper to 2.8 billion metric tons. This would fit into a cube...
Full view of salt, sodium, chlorine sample
To maintain our standard of living, each person in the United States requires over 38,449 pounds of minerals each year: 9,426 pounds of stone 6,768 pounds of sand and gravel 655 pounds of cement 142 pounds of clays 338 pounds of salt 244 pounds of iron ore 195 pounds of phosphate rock 34 pounds of soda ash 28 pounds of aluminum 13 pounds of copper...