Flat, planar, non-elongate crystals are described as having a tabular habit. Tabular crystals are thicker than platy crystals.

Usually refers to quartz grains, which have undergone partial recrystallisation, producing irregular, sutured grain boundaries.

A crystal displaying some, but not all of its characteristic crystal faces is called subhedral.

This is a measure of density. It is the ratio of the density of the substance being described (e.g. a mineral) to the density of water. Olivine has a specific density, D = 3.222, which means that olivine is 3.222 times more dense than water. Since water has a density of 1 g cm^-3, olivine has a density of 3.22 g cm^-3.

Minerals such as quartz have a discrete composition and thus one chemical formula (in this case SiO₂). Other minerals can have a range of compositions between two or three end-member chemical formulae. Olivine, for example, has an end-member composition called forsterite (FeSiO₄). By gradually replacing Fe atoms with Mg atoms, a continuous range of compositions can be produced ending at the Mg end-member, fayallite (MgSiO₄). The range of compositions is called a solid solution.

A single twin plane, producing two twins, within one mineral grain is called a simple twin. The clinopyroxene augite can display simple twinning. Simple twins are occasionally referred to as Carlsbad twins.

Schistosity is a type of foliation (planar fabric) found within metamorphosed rocks. It is produced under moderate metamorphic conditions by the alignment and significant recrystallisation of mineral grains. Recrystallised grains are large enough to be seen with the naked eye.