This determines a mineral's many physical properties. Some minerals such as malachite are always one color, but minerals such as quartz exhibit many colors due to impurities in their chemical structure. Cleavage refers to a smooth parting. There are three directions of symmetry within a crystal. Some have no cleavage at all.
Fracture describes an irregular break on the surface of a mineral that has no cleavage.
There are many terms used to describe this, such as uneven, splintery, and conchoidal. Specimens harder than the plate will leave no streak. The resulting crystals take on shapes such as cubes, six sided barrels and bipiramids. Metallic luster is obvious and is classed as either bright or dull.