metamorphic
Greenstone (Greywacke or Nephrite Jade variant)
Metamorphosed mafic igneous or sedimentary rock (e.g., Actinolite-Chlorite Schist)
Hardness: 5-7 (Mohs scale); Color: Gray-green to dark forest green; Luster: Waxy to dull (pebble surface); Crystal structure: Monoclinic (fine-grained/cryptocrystalline); Specific Gravity: 2.8 - 3.4.
- Hardness
- 5-7 (Mohs scale)
- Color
- Gray-green to dark forest green
- Luster
- Waxy to dull (pebble surface)
Identified More metamorphic →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 5-7 (Mohs scale); Color: Gray-green to dark forest green; Luster: Waxy to dull (pebble surface); Crystal structure: Monoclinic (fine-grained/cryptocrystalline); Specific Gravity: 2.8 - 3.4.
Formation & geological history
Formed via low-grade metamorphism of mafic protoliths (like basalt) or sedimentary deposits in subduction zones. Often associated with greenschist facies metamorphism from the Paleozoic or Mesozoic eras.
Uses & applications
Used for decorative gravel, landscaping, historical tool-making (celts and adzes), and as a semi-precious gemstone (if high-quality Nephrite).
Geological facts
Greenstone was highly prized by indigenous cultures, such as the Māori (Pounamu) and early Europeans, for its toughness and ability to hold a sharp edge when carved into tools.
Field identification & locations
Identify in the field by its distinct greenish hue when wet, extreme toughness (resistance to shattering), and smooth, river-worn texture. Commonly found in riverbeds and beaches in New Zealand, the Pacific Northwest, and California.
More like this
