Where is Quartzite found?
Metamorphic rock (Quartzite)
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Open the appQuartzite 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 Quartzite
Appalachian Mountains, USA
Extensive quartzite formations, such as the Erwin Quartzite and Weverton Formation, are found throughout the Appalachian Mountains, particularly in the Blue Ridge and Valley and Ridge provinces. These are often Proterozoic to early Paleozoic in age.
Baraboo Range, Wisconsin, USA
Famous for the Baraboo Quartzite, a Precambrian (Paleoproterozoic) formation known for its distinctive purple-red color and excellent preservation of sedimentary structures.
Scotland
The Cambrian-age Eriboll Quartzite in the Northwest Highlands is a classic example, forming prominent peaks and ridges.
Brazil
Significant deposits, particularly in Minas Gerais, known for high-quality quartzite used in construction and as a source of silicon.
India
Various regions, including Rajasthan and parts of the Himalayas, contain extensive quartzite formations of different ages.
Canada
Found in the Canadian Shield and other orogenic belts, such as the Rocky Mountains.
Collecting tips
- Look for Hardness. Quartzite is extremely hard (Mohs 7). It will scratch steel and cannot be scratched by a knife or common glass. This is a key differentiator from softer rocks like marble or even some sandstones.
- Examine Fracture Pattern. Unlike sandstone, which tends to break around individual sand grains, quartzite breaks through the grains, resulting in a smooth, often conchoidal fracture surface. This 'through-grain' fracture is diagnostic.
- Check for Grain Interlocking. The grains in quartzite are tightly interlocked and recrystallized, making it difficult to dislodge individual grains with your fingers or a tool. Sandstone, in contrast, often feels gritty and individual grains can be rubbed off.
- Observe Luster. Quartzite typically exhibits a vitreous (glassy) to greasy luster on freshly broken surfaces due to the quartz composition.
- Consider Geological Context. Quartzite is found in metamorphic terrains, often associated with mountain ranges or ancient shield areas. Look for it in areas where regional metamorphism has occurred.
- Acid Test (for differentiation from marble). Quartzite will not react with dilute hydrochloric acid, as it is composed of silica. Marble, which is composed of calcite, will effervesce vigorously. This is a crucial test to distinguish white quartzite from white marble.
Quick Check
- Color:
- White, gray, pink, red, yellow, green, blue
- Luster:
- Vitreous (glassy) to greasy
- Streak:
- White (as it is harder than the streak plate)
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