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An introduction to minerals and rocks under the microscope
An introduction to minerals and rocks under the microscope

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1.3.5 Density

Density is a measure of how heavy an object is for a given volume. You can get a general idea of the relative densities of different minerals just by picking them up: a piece of galena feels heavier than a piece of quartz of the same size. The density of a mineral depends on its chemical composition, the type of bonding and its crystal structure. The standard unit of density is kg m−3. Examples of the relative densities of various minerals compared with water at room temperature (about 1000 kg m−3) are shown in Table 1. The relationship between density and crystal structure is explored further in Section 1.4.

Table 1 Relative densities of various minerals
Mineral Symbol/formula Relative density at room conditions (compared with water = 1.0)
graphite  C 2.2
quartz  SiO2 2.7
diamond  C 3.5
barite  BaSO4 4.5
galena  PbS 7.6
silver  Ag 10.5
gold  Au 19.3