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In addition, it must be hard and durable. Its value increases if it is also rare.The beauty of a gem is measured in terms of its clarity, brilliance, and color. Comments
Density: The density of a mineral is an important natural property, although not easily tested in the field. Heaviest are the gold and platinum metals (density close to 20). Silicates weigh in between 2.5 and 3.5, ores between 4 and 8. Cleavage: the cleavage of a mineral refers to how it breaks.