Mineralology Important Vocab

Crystal Habit

includes the terminology that covers the way mineral grains are shaped and intergrown in rocks and mineral deposits, AKA living habits

Crystal Form

The collection of crystal faces that make up a crystal is referred to as the ______ ____. This terminology includes shapes such as cubes and octahedrons, as well as a variety of other shapes, such as prisms, pinacoids, and pyramids. AKA dress form

Crystal Class

For each specific point group symmetry, there is a unique set of crystal forms, this unique set of forms is a ________ _____. Given there are 32 point groups, there are therefore 32 ________ ____, one for each point group

Crystal Shape

The internal arrangement of atoms in a mineral influences its form when crystallized

Crystal Structure

An orderly array of atoms, ions, or molecules makes up the structure. Atoms, atomic groupings, or molecules are joined. Crystals are composed of atoms arranged in a lattice with a regular internal structure

birefringence

The difference in the index of refraction between the slow ray and the fast ray

pleochroism

Describes a mineral that changes color in plane-polarized light with rotation under the petrographic microscope

unit cell

For a Bravais lattice, the volume outlined by lattice nodes that is stacked repeatedly via only translation to create the entire crystal lattice. Within the ___ ____ is the smallest collection of bonded atoms that retains all the properties of the mineral.

anisotropic

isotropic

isogyres

The dark bands found in interference figures

crystal zone

A region of a mineral with similar orientation and/or composition; also a collection of crystal faces, all of which are parallel to a common line called a zone axis

solid solution

Mineral compositional variation due to more than one element being found within specific crystal structural sites