Quartz gemstone information (original) (raw)

Varieties/Types:

Amethyst - A purple variety of Quartz.

Ametrine - A mixture of Amethyst and Citrine in the same crystal.

Aqua Aura - Clear quartz artificially coated with thin layer of metal to turn it iridescent.

Chalcedony - A cryptocrystalline variety of Quartz.

Agate - A banded variety of Chalcedony.

Iris Agate - An iridescent variety of Agate.

Onyx - A monochromatic Agate with black and white banding.

Sardonyx - A monochromatic Agate with red/brown and either black or white banding.

Binghamite - Chatoyant Chalcedony with fibres of hematite/goethite.

Bloodstone - A dark green/greenish-blue Chalcedony with small red blood-like spots.

Carnelian - A red to orange variety of Chalcedony.

Chrysoprase - A green Chalcedony coloured by inclusions of Ni minerals.

Dendritic Agate - A chalcedony containing contrasting branching, or dendritic, mineral inclusions.

Moss Agate - A translucent chalcedony containing green strands of chlorite.

Fire Agate - A variety of Agate containing iridescent spheroids of limonite.

Jasper - Jasper is a dense, opaque, microcrystalline variety of Chalcedony.

Dallasite - A variety of Jasper from Vancouver Island, British Columbia, Canada.

Orbicular Jasper - Jasper containing numerous spherical inclusions.

Petrified Wood - A decorative type of fossil wood where the original organic material has been replaced - usually by chalcedony, agate, opal, etc.

Pietersite - Chalcedony with embedded fibers of amphibole minerals, causing chatoyancy.

Sard - A brown to brownish-red translucent variety of Chalcedony.

Citrine - A yellow to yellow-orange or yellow-green variety of Quartz.

Iris Quartz - A quartz showing rainbow colours.

Merlinite - Drusy quartz over psilomelane.

Mystic Quartz - Clear cut quartz coated with thin layer of titanium on pavilion.

Prase - Prase is a leek-green variety of Quartz.

Aventurine - A variety of Quartz containing glistening fragments, usually of mica, but sometimes hematite, goethite or chlorite.

Rock Crystal - A transparent colourless variety of Quartz.

Smoky Quartz - Smoky-grey, brown to black variety of Quartz.

Morion - Sometimes synonymous with Smoky quartz, but often reserved for nearly black Smoky quartz.

Tiger's Eye - Chatoyant yellowish-brown variety of Quartz.

All colors, mostly amethyst, citrine, ametrine: colors are usually intense. Standard tests limited: needle-like 2 phase inclusions, dust-like "breadcrumb" planes, whitish wisps. In synthetic quartz, if present, twinning may create a distinctive lfame-like pattern or may be seen as very thin parallel lines showing interference colors with diagnostic striated appearance. Synthetic blue: Chelsea - red. - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 7
Synthetic quartz: mostly untwinned, rarely triangular sectors with interference colours, "bread crumbs", residues of the seed plate - Gemmological Tables, Ulrich Henn and Claudio C. Milisenda, 2004, p 9