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Classical compound, Ancient Greek ἀλλότριος (allótrios, “foreign”) + -morph.
Etymology from Wiktionary, CC BY-SA 4.0.
allotriomorph
Today it means: A mineral that did not develop its otherwise typical external crystal form because of late crystallization between earlier formed crystals, typical of matrix minerals in rapidly crystallizing volcanic lavas and shallow igneous intrusions. Full definition →