The crystal quartz — also known as rock crystal or clear quartz — is probably the most widely distributed mineral in the Earth’s crust. Nevertheless, a good, colorless quartz specimen with its clear, spring water shimmering pyramid-shaped ends remains one of the most fascinating minerals in the world.
Structure and Composition
Quartz is silicon dioxide (SiO₂) with a trigonal structure. Its hardness of 7 on the Mohs scale makes it one of the most resilient minerals in nature — harder than glass (5.5), but softer than topaz (8) and sapphire (9).
The typical crystal form is a hexagonal prism, capped at both ends with flattened pyramids. Under ideal growth conditions, the crystals develop smooth and shiny surfaces with characteristic horizontal stripes.
Quartz Variants
Quartz is a mineralogical “family” that encompasses numerous color variants:
- Clear Quartz: colorless and transparent — the classic “rock crystal”
- Amethyst: violet, due to traces of irradiated iron
- Citrine: yellow-orange, due to oxidized iron
- Rose Quartz: pale pink, due to titanium and manganese
- Smoky Quartz: gray-brown, due to natural irradiation
- Adventurine Quartz: quartz with fuchsite inclusions that create a sparkling effect
Where to Find It
Quartz forms in almost all geological environments: in granitic pegmatites (where the largest crystals grow), in hydrothermal veins, in sedimentary rocks (such as sand and sandstone), and even in metamorphic rocks. Crystals of gemological and collector quality mainly come from:
- Brazil (Minas Gerais): the largest single crystals in the world, often over a meter long
- Madagascar: exceptional optical quality, very commonly used in precision optics
- Switzerland and Austria: alpine crystals in Stiss, often of great purity and with chlorite ghosts inside
- Arkansas, USA: industrial and collector production on a large scale
The “Phantom” Quartz
One of the most sought-after variants by collectors is the phantom quartz: During crystal growth, deposits of green chlorite or other minerals settled on the surface, which were then covered with clear quartz. The result is the silhouette of a smaller crystal, visible within the larger one — a kind of “imprint” of the geological past of the piece.
How to Choose a High-Quality Specimen
- Purity: For transparent quartz, purity is crucial. A crystal without cloudiness, internal fractures, or opaque inclusions is very rare and valuable.
- Intact Ends: The pyramid-shaped tips are the most fragile part — the absence of chips significantly increases the value.
- Size: For the same quality, each additional centimeter represents a non-linear increase in value.
- Matrix Base: A crystal that is still rooted in its host rock (matrix) has a higher collector value and presents better in display.
In the CharmeIs catalog, you will find selected quartz from various regions of origin — from the alpine Swiss crystal to Brazilian clusters — always with documented provenance and photography of the actual specimen.