mineral
Plagioclase Feldspar
Plagioclase (NaAlSi3O8 - CaAl2Si2O8)
Hardness: 6-6.5 Mohs; Color: White to grey; Luster: Vitreous to pearly; Crystal structure: Triclinic; Cleavage: Two directions at nearly 90 degrees; Specific gravity: 2.62-2.76.
- Hardness
- 6-6
- Color
- White to grey
- Luster
- Vitreous to pearly
Identified More mineral →
Explore Plagioclase Feldspar in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6-6.5 Mohs; Color: White to grey; Luster: Vitreous to pearly; Crystal structure: Triclinic; Cleavage: Two directions at nearly 90 degrees; Specific gravity: 2.62-2.76.
Formation & geological history
Forms in igneous rocks like basalt, granite, and diorite as magma cools, as well as in metamorphic rocks. It is archaic, dating back to the formation of the Earth's crust.
Uses & applications
Used in the ceramics and glass industry to improve durability and resistance. Some varieties like moonstone or labradorite are used in jewelry. Also used as an aggregate in construction.
Geological facts
Feldspars are the most abundant mineral group in the Earth's crust. Plagioclase is a solid solution series ranging from sodium-rich albite to calcium-rich anorthite.
Field identification & locations
Identify in the field by its white color, hardness (greater than steel), and the presence of fine, parallel grooves called polysynthetic twinning striations on cleavage surfaces.
More like this
Other mineral specimens
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Schist
Schist
Metamorphic
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Nephrite Jade
Nephrite
Mineral/Rock
Banded Gneiss (River Rock/Pebble)
Gneiss (specifically a banded variety often found as a river rock)
Metamorphic Rock