Editing Mineral (section)

===Specific gravity===
[[File:Calcite-Galena-elm56c.jpg|right|thumb|[[Galena]], PbS, is a mineral with a high specific gravity.]]
[[Specific gravity]] numerically describes the [[density]] of a mineral. The dimensions of density are mass divided by volume with units: kg/m<sup>3</sup> or g/cm<sup>3</sup>. Specific gravity is defined as the density of the mineral divided by the density of water at 4&nbsp;°C and thus is a dimensionless quantity, identical in all unit systems.{{sfn|Nesse|2000|p=97}} It can be measured as the quotient of the mass of the sample and difference between the weight of the sample in air and its corresponding weight in water. Among most minerals, this property is not diagnostic. Rock forming minerals&nbsp;– typically silicates or occasionally carbonates&nbsp;– have a specific gravity of 2.5–3.5.<ref name="DG4344">{{harvnb|Dyar|Gunter|2008}}, pp. 43–44</ref>

High specific gravity is a diagnostic property of a mineral. A variation in chemistry (and consequently, mineral class) correlates to a change in specific gravity. Among more common minerals, oxides and sulfides tend to have a higher specific gravity as they include elements with higher atomic mass. A generalization is that minerals with metallic or adamantine lustre tend to have higher specific gravities than those having a non-metallic to dull lustre. For example, [[hematite]], Fe<sub>2</sub>O<sub>3</sub>, has a specific gravity of 5.26<ref>{{cite web|url=https://www.mindat.org/min-1856.html|title=Hematite|publisher=Mindat.org|access-date=3 April 2018|archive-date=11 May 2020|archive-url=https://web.archive.org/web/20200511194050/https://www.mindat.org/min-1856.html|url-status=live}}</ref> while [[galena]], PbS, has a specific gravity of 7.2–7.6,<ref>{{cite web|url=https://www.mindat.org/min-1641.html|title=Galena|publisher=Mindat.org|access-date=3 April 2018|archive-date=11 May 2020|archive-url=https://web.archive.org/web/20200511194055/https://www.mindat.org/min-1641.html|url-status=live}}</ref> which is a result of their high iron and lead content, respectively. A very high specific gravity is characteristic of [[native metal]]s; for example, [[kamacite]], an iron-nickel alloy common in [[iron meteorite]]s has a specific gravity of 7.9,<ref>{{cite web|url=http://webmineral.com/data/Kamacite.shtml#.WsQTQGbn9SM|access-date=3 April 2018|publisher=Webmineral.com|title=Kamacite|archive-date=13 December 2017|archive-url=https://web.archive.org/web/20171213044915/http://webmineral.com/data/Kamacite.shtml#.WsQTQGbn9SM|url-status=live}}</ref> and gold has an observed specific gravity between 15 and 19.3.<ref name="DG4344" /><ref>{{cite web|url=https://www.mindat.org/min-1720.html|title=Gold|publisher=Mindat.org|access-date=3 April 2018|archive-date=27 April 2018|archive-url=https://web.archive.org/web/20180427101610/https://www.mindat.org/min-1720.html|url-status=live}}</ref>