Of the 1.52 billion metric tons of copper discovered to date, 56% is found in just four countries on earth. All the copper discovered thus far would fit in a cube 550 meters on a side.
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.
A naturally occurring inorganic element or compound having an orderly internal structure and characteristic chemical composition, crystal form, and physical properties.  
Granite is an igneous rock that is composed of four minerals. These minerals are quartz, feldspar, mica, and usually hornblende. Granite forms as magma cools far under the earth's surface. Because it hardens deep underground it cools very slowly. This...
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.  
White gold was originally developed to imitate platinum, and is usually an alloy containing 25% nickel and zinc. If stamped 18 karat, it would be 75% pure gold.  
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 biotite mica can mimic flake gold.
A rock is an aggregate of one or more minerals; or a body of undifferentiated mineral matter. 
For information on former U.S. Bureau of Mines (USBM) programs or publications, please contact the following sources: USBM PublicationsNational Technical Information Service (NTIS)Information Phone: 703-605-6050Order Phone: 1-888-584-8332Bureau of Mines...
Acid precipitation affects stone primarily in two ways: dissolution and alteration. When sulfurous, sulfuric, and nitric acids in polluted air react with the calcite in marble and limestone, the calcite dissolves. In exposed areas of buildings and...