Science, Maths & Technology

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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
MineralSymbol/formulaRelative density at room conditions (compared with water = 1.0)
graphite C2.2
quartz SiO22.7
diamond C3.5
barite BaSO44.5
galena PbS7.6
silver Ag10.5
gold Au19.3