Equant/Stout – Length, width, and breadth roughly equal
2023-03-13
Common examples include: apophyllite, olivine, garnetContinue Reading
Enantiomorphic – Mirror-image habit (i.e. crystal twinning) and optical characteristics; right- and left-handed crystals
2023-03-13
Common examples include: gypsum, quartz, plagioclase, stauroliteContinue Reading
Dodecahedral – Dodecahedron-shaped, 12-sided
2023-03-13
Common examples include: garnet, pyriteContinue Reading
Cubic – Cube shape
2023-03-13
Common examples include: fluorite, pyrite, galena, haliteContinue Reading
Sceptered – Crystal growth stops and continues at the top of the crystal, but not at the bottom
2023-03-13
Common examples include: hedenbergite, quartzContinue Reading
Nodular/Tuberose – Deposit of roughly spherical form with irregular protuberances
2023-03-13
Common examples include: agate (and other chalcedony)Continue Reading
Massive/Compact – Shapeless, no distinctive external crystal shape
2023-03-13
Common examples include: limonite, turquoise, cinnabar, quartz, realgar, lazuriteContinue Reading
Hemimorphic – Doubly terminated crystal with two differently shaped ends
2023-03-13
Common examples include: hemimorphite, elbaiteContinue Reading
Amygdaloidal – Like embedded almonds
2023-03-13
Common examples include: heulandite, subhedral zircon Amygdules or amygdales (/əˈmɪɡdjuːlz, -deɪlz/) form when the vesicles (pores from gas bubbles in lava) of a volcanic rock or other extrusive igneous rock are infilled with a secondary mineral, such as calcite, quartz, chlorite, or one of the zeolites. Amygdules usually form after the rock has been emplaced, and are often associated with low-temperature alteration. Amygdules may often be concentrically zoned.Continue Reading
Wheat Sheaf – Aggregates resembling hand-reaped wheat sheaves
2023-03-13
Common examples include: stilbiteContinue Reading
Tabular/Blocky/Stubby – More elongated than equant, slightly longer than wide, flat tablet-shaped
2023-03-13
Common examples include: feldspar, topaz, vanadiniteContinue Reading
Stellate – Star-like, radial aggregates radiating from a “star”-like point to produce gross spheres (crystals are not or weakly separated and have similar lengths)
2023-03-13
Common examples include: pyrophyllite, aragonite, wavellite, “pyrite suns”Continue Reading
