eli5 – what’s the difference between rocks, minerals, gems, gemstones, crystals, geodes, etc?

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eli5 – what’s the difference between rocks, minerals, gems, gemstones, crystals, geodes, etc?

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Mineral are inorganic elements, molecules or compound with define characteristics. For example, Quartz is a mineral made of SiO2 with a crystalline structure.

Rock is an aggregate of one or more minerals. For example, Granite is often composed of quartz, feldspar and plagioclase. Pressure and time forced all those minerals together to form a rock, but you can still identify each type of minerals inside the rock.

Gems and Gemstones mean the same thing, Gem is just a shorten name. Gems are minerals (like ruby), rocks (like opal) or organic material (like pearl) that are used in jewelry. Whatever is used in jewelry can technically be called Gem, but usually it’s reserved for the finish product (extracted, cut, polished, etc).

Crystals are something with an highly ordered microscopic structure. It’s basically a structure that repeat itself in all direction. In most case, it’s a mineral that can form a crystal, but Ice also form as a crystal and some living organism can also form a crystalline structure. An amorphous structure is more random.

Geodes are hollow rock, with a mineral matter inside. It’s those rock that look normal on the outside, but when you break them you see beautiful colors and pattern.

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