Elements

Specimen of 
Silver from Batopilas Most of the objects, including minerals, we encounter are compounds composed of several chemical elements, and only very few are pure elements. Technically an 'element' can be described as 'atoms with the same number of protons,' and a little more loosely as 'the smallest units with identical chemical properties.'
You are probably familiar with several elements, including metals like iron, copper, silver, and gold. Oxygen is a gaseous element, and sulfur is a non-metallic, solid element. Most of what surrounds us is made up of several elements, that is chemical compounds. The elements can either be bonded as ions (as sodium and chloride in kitchen salt), weakly bonded by so-called van der Waal bonds as in alloys (steel is an alloy of the elements iron, nickel, cobalt, and possibly others, depending on its use), or unbonded as in the atmosphere (it is chiefly composed of the element nitrogen, contains the element oxygen, and a few others in small amounts). Effectively, we see very few pure elements in our daily lives, and only aluminum foil and copper wire are at the same time widely used and comparatively pure elements.
Most minerals are compounds, and only few of the approximately 100 known elements are found pure and unbound in nature. Some elements like Copper, Silver, Gold, Carbon (Graphite and Diamond), and Sulfur are quite abundant as minerals in nature. Platinum group metals (platinum, osmium, iridium, etc.), Selenium, and native Arsenic [not to be confused with the 'arsenic' used to bump off rich aunts in crime novels, which is an oxide of arsenic] may be locally abundant, but have a limited global distribution. Interestingly, native Iron is very rare in nature [iron is mostly bound as an oxide], and native aluminum is unknown.
Specimen of 
Sulfur with Asphalt from Sicily

Bibliography

Blackburn, William H. & William H. Dennen. 1997. Encyclopedia of mineral names. Canadian Mineralogist, special publication 1.
Gaines, Richard W., H. Catherine W. Skinner, Eugene E. Foord, Brian Mason, Abraham Rosenzweig & Vandall T. King. 1997. Dana's new mineralogy: the system of mineralogy of James Dwight Dana and Edward Salisbury Dana, 8th ed.
Hintze, Carl (ed.) 1897-1939. Handbuch der Mineralogie.
Ramdohr, Paul & Hugo Strunz. 1980. Klockmann's Lehrbuch der Mineralogie, 16th ed.
Sinkankas, John. 1964. Mineralogy.


This page is authored by Claus Hedegaard.