| Quartz gems |
The Quarz gems comprise several different groups with the same or similar chemical properties, all crystallizing in the trigonal crystal system. All varieties of a group have similar physical properties. There are the fully crystalline quartz and the cryptocrystalline quartz.
| Rock Crystal | A colourless water-clear quartz, forming large
crystals. Occurances: Brazil, Madagascar, Switzerland and Sri Lanka.
|
| Brown Quarz | Also known as Smoky Quartz, has a clear brown
colour caused by a powerful natural irradiation, which leads to a colloidal
distribution of silicon atoms in the structure.
Occurences: same as Rock Crystal. |
| Amethyst | The most longing gem of the quartz family. Its
colour is a wide range and varies from nearly colourless to a glorious
purple. Occurences: Brazil, Uruguay, Madagascar, Russia
and Sri Lanka.
|
| Citrine | The yellow quartz varies in colour from a light
golden yellow to a reddish-yellow.
Occurences: USA, Brazil, Madagascar, Russia. |
| Rose Quartz | A grainy aggregate with a rose-red colour. Transparent
gems are very seldom, in most cases the material is only tranlucent and
very cloudy with fissures.
Occurences: USA, Brazil, Madagascar, South-Africa, Austria. |
| Jasper | Jasper is a heterogenous mass , heavily pigmented
with colourful minerals, its colour varies from yellow and brown over red
to green.
Occurences: worldwide. |
| Plasma | Plasma is a dark green stone coloured by
green mineral chlorite.
Occurences: USA |
| Prase | A dark green material, coloured by included
actinolite crystals.
Occurences: Germany, Finland, Austria. |
| Quartz Cat´s Eye | Cat´s Eyes owe their chatoyancy to a multitude
of fibres of fine asbestos that are oriented parallel.
Occurence: South Africa |
| Hawk´s Eye | Hawk´s Eyes ares a fibrous, opaque aggragate
with inclusions of crcidolite.
Its colour varies from a bluish-grey to a bluish green. Occurence: South Africa |
| Tiger´s Eye | A Tiger´s Eye is a Hawk´s Eye, altered
by decomposition into silica, stained by hydrous iron oxide with a brwnish
colour.
Occurence: South Africa |
| Chalcedony | A fibrous aggregate with a bluish-white colour.
Occurences: Brazil, Madagascar, India. |
| Chrysoprase | An apple- green-coloured material from Poland and Australia. |
| Sard | A reddish-brown, tranlucent chalcedony from Brazil, coloured by iron-oxide |
| Cornelian | Even more red than sard. Occurence: Brazil |
| Agate | Agate is a banded chalcedony, most commonly used
for figurines, ash-trays....
Occurences: Brazil, Uruguay. |
| Moss Agate | Moss Agate is a transparent dendritic agate with
inclusions of other minerals. It is very longing, because these inclusions
may look similar to pictures of landscapes, trees, animals....
Occurences: USA, India, China. |
