"Mineraloid" is a name given to a handful of substances that don't quite qualify as true minerals because they never form crystals (that is, they are amorphous) and don't have a precise chemical formula. Nevertheless, mineraloids are found in pure pieces and have a consistent composition.
Geologists restrict the mineraloids to inorganic substances, but tradition places some other things among the mineraloids. This list includes them all.
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 Amber |  Jet |  Lechatelierite |  Limonite |
 Obsidian |  Opal |  Palagonite |  Pearl |
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