Where is Quartz in host rock found?
Quartz (SiO2) in igneous or metamorphic rock
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Open the appQuartz in host rock occurs in specific geological environments. Knowing where to look, and in what kind of rock, is the difference between going home empty-handed and finding a great specimen.
Where to find Quartz in host rock
Worldwide
Quartz is one of the most common minerals on Earth and is found in igneous and metamorphic rocks on every continent. Significant occurrences of quartz-rich host rocks are found in major mountain ranges, continental shields, and volcanic arcs.
Appalachian Mountains, USA
Extensive metamorphic terrains containing quartz-rich schists and gneisses, as well as granitic intrusions.
Brazilian Shield
Known for large granitic intrusions and metamorphic complexes with abundant quartz.
Fennoscandian Shield, Europe
Contains vast areas of granite, gneiss, and quartzite.
Collecting tips
- Look for glassy luster. Quartz grains in a host rock will often stand out due to their characteristic glassy luster, especially on a freshly broken surface.
- Check for hardness. Quartz is hard (Mohs 7). It will scratch glass and most common metals. This can help distinguish it from softer minerals like feldspar (Mohs 6-6.5) or calcite (Mohs 3).
- Observe fracture. Unlike minerals with cleavage, quartz breaks with a conchoidal (shell-like) fracture, which can be visible on larger grains.
- Consider the host rock context. In granite, quartz will be one of the primary light-colored minerals alongside feldspar. In quartzite, the rock will be almost entirely composed of interlocking quartz grains. In gneiss or schist, quartz will appear as elongated or granular light-colored bands or lenses.
Quick Check
- Color:
- Colorless, white, gray, smoky
- Luster:
- Vitreous to greasy
- Streak:
- White
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