Where is Feldspar found?
Feldspar group
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Open the appFeldspar 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 Feldspar
Worldwide
Feldspars are globally distributed due to their abundance in Earth's crust. Significant deposits for industrial use are found in countries like the USA (North Carolina, South Dakota), Canada, Norway, Sweden, Germany, France, Italy, India, China, and Brazil.
Igneous Intrusions
Large, well-formed crystals can be found in pegmatites, which are coarse-grained igneous rocks often associated with granitic intrusions.
Volcanic Rocks
Phenocrysts of feldspar are common in many volcanic rocks such as basalts, andesites, and rhyolites.
Metamorphic Terrains
Abundant in high-grade metamorphic rocks like gneisses and schists, particularly in ancient shield areas.
Collecting tips
- Look for Cleavage. The most reliable field identification for feldspar is its two distinct cleavage planes, which typically intersect at or close to 90 degrees. This distinguishes it from quartz, which has no cleavage.
- Check for Striations. On plagioclase feldspars, look for fine, parallel striations (polysynthetic twinning) on cleavage surfaces. This is a definitive characteristic for plagioclase.
- Assess Hardness. Feldspar has a Mohs hardness of 6 to 6.5, meaning it can scratch glass but cannot be scratched by a steel knife. This helps differentiate it from softer minerals.
- Observe Color and Luster. While variable, the vitreous to pearly luster and common colors (white, gray, pink) are good initial indicators. Alkali feldspars often have a pinkish hue, while plagioclase is typically white to gray.
Quick Check
- Color:
- White, gray, pink, red, green, yellow, brown
- Luster:
- Vitreous to pearly
- Streak:
- White
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