metamorphic or sedimentary
Greenstone / Glauconitic Siltstone
Metabasalt or Glauconite-rich Sedimentary Rock
Hardness: 3-6 (depending on mineralogy); Color: Dull green to teal-grey; Luster: Earthy to waxy; Texture: Fine-grained, smooth water-worn surface.
- Hardness
- 3-6 (depending on mineralogy)
- Color
- Dull green to teal-grey
- Luster
- Earthy to waxy
Identified More metamorphic or sedimentary →
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Physical properties
Hardness: 3-6 (depending on mineralogy); Color: Dull green to teal-grey; Luster: Earthy to waxy; Texture: Fine-grained, smooth water-worn surface.
Formation & geological history
Usually formed from the low-grade metamorphism of mafic igneous rocks (forming greenstone) or the accumulation of iron-rich silicates in marine environments (forming glauconite-rich siltstones).
Uses & applications
Commonly used as decorative landscaping stones, road aggregate, and sometimes as a pigment (green earth). High-quality greenstone is used for carving.
Geological facts
Greenstone belts represent some of the oldest known geological formations on Earth, documenting early tectonic processes millions to billions of years ago.
Field identification & locations
Identify in the field by its distinct greenish hue and fine-grained texture. Often found as rounded river or beach cobbles. Non-reactive to weak acids.
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Mineral
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Milky Quartz
Quartz (Silicon Dioxide - SiO2)
mineral
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Milky Quartz
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mineral
Pebble (likely Quartz or Chert)
SiO₂ (Silicon Dioxide) - referring to the likely main mineral composition, Quartz. If it's chert, the scientific name remains SiO₂ with a microcrystalline structure.
Sedimentary Rock