Editing Geology (section)

===Minerals===
{{main|Mineral}}
Minerals are naturally occurring [[Chemical element|element]]s and [[Chemical compound|compound]]s with a definite homogeneous chemical composition and an ordered atomic arrangement.

Each mineral has distinct physical properties, and there are many tests to determine each of them. Minerals are often identified through these tests. The specimens can be tested for:<ref>{{cite web|title=Mineral Identification Tests|url=http://jersey.uoregon.edu/~mstrick/MinRockID/MinTests.html|website=Geoman's Mineral ID Tests|access-date=17 April 2017|archive-date=9 May 2017|archive-url=https://web.archive.org/web/20170509215641/http://jersey.uoregon.edu/~mstrick/MinRockID/MinTests.html|url-status=live}}</ref>
* Color: Minerals are grouped by their color. Mostly diagnostic but impurities can change a mineral's color.
* [[Streak (mineralogy)|Streak]]: Performed by scratching the sample on a [[porcelain]] plate. The color of the streak can help identify the mineral.
* Hardness: The resistance of a mineral to scratching or indentation.
* Breakage pattern: A mineral can either show fracture or [[Cleavage (crystal)|cleavage]], the former being breakage of uneven surfaces, and the latter a breakage along closely spaced parallel planes.
* [[Lustre (mineralogy)|Luster]]: Quality of light reflected from the surface of a mineral. Examples are metallic, pearly, waxy, dull.
* [[Specific gravity]]: the weight of a specific volume of a mineral.
* Effervescence: Involves dripping [[hydrochloric acid]] on the mineral to test for fizzing.
* Magnetism: Involves using a magnet to test for [[magnetism]].
* Taste: Minerals can have a distinctive taste such as [[halite]] (which tastes like [[table salt]]).