Whenever we talk about minerals, especially our favorite minerals, we use all sorts of descriptive terms that don’t seem to have anything to do with one of the six crystal systems. Mineral specimens are commonly described as dendritic, acicular, columnar, striated, botryoidal, banded, and prismatic, acicular.
High temperature mineral deposits are where very complex fl uorite crystals often form.
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These terms are the language of crystal habits and are an integral part of a conversation when we describe mineral specimens. While using such terms, we seldom think about why a particular term works for us. I doubt we realize these terms are the direct result of two things, the mineral’s internal atomic structure and the role it plays in a mineral’s development and the effects of the environment on a mineral during formation. We already know when a mineral forms, it develops as one of the recognized crystal systems: isometric, hexagonal, monoclinic, triclinic, tetragonal, or orthorhombic. You may also come across a seventh system, trigonal. This is actually a sub-system based on two basic crystal forms in the hexagonal system.