How Rock Crystals Are Formed
Other People Are Reading
-
Basics of Crystals
-
Crystals are the molecular arrangements which form minerals. A crystal has a polyhedral form, making it a geometric solid. Crystals are studied based on the shapes making up their faces, sides and bases, as well as their planes of symmetry. From the basic crystal structure comes a lattice, a regular repetition of the crystal's structure in three dimensions. The process by which crystallization occurs is divided into two phases: nucleation and growth. In nucleation a nucleus (or kernel) of a mineral is present. This kernel forms from randomly scattered constituent material of a mineral. Often, this occurs on an impurity which will eventually give the mineral crystal (if a gemstone) some color. Once a kernel exists, growth (or enlargement) can occur if additional layers of the appropriate matter accumulate.
Rock Crystal Structure
-
Rock crystal, or colorless quartz, is a silicon oxide and belongs in the hexagonal system. Generally, the crystals form as hexagonal prisms with pyramidal ends. Any striations run perpendicular to the crystal's length. Rock crystal is often found twinned with other minerals. It has poor cleavage and conchoidal fracture (smooth, shell-like bumps or indentations). The crystals may also contain gas or liquid bubbles which are visible to the naked eye.
-
Rock Crystal Formation
-
Colorless quartz is one of the commonest minerals found in the Earth's crust. And rock crystal is the most distributed variety of quartz. The mineral crystallizes from igneous magma and occurs in plutonic rocks, which include granites, granodiorites and tonalites. It also occurs in hypabyssal formations (or granite porphyries, pegmatites and the like) and in volcanic rocks such as quartz porphyry and rhyolites. It is stable in sedimentary conditions as well, either as a deposited mineral or as cement in consolidated rocks such as sandstone.
More about Rock Crystal
-
The name quartz comes from the Greek word "krustallos" meaning ice. In ancient times, it was believed to have been ice made by the gods. Others have believed it was petrified ice. Since the middle ages, fortunetellers have used crystal balls made of rock crystal in plying their trade. Today, we use rock crystal in lamps, lenses and in manufacturing glass and precision instruments. In laboratories, synthetic rock crystal has been produced for use in watches since 1950.
-
