mineral
Feldspar (likely Orthoclase or Plagioclase)
Tectosilicate Feldspar (KAlSi3O8 to (Ca,Na)(Al,Si)4O8)
Hardness: 6-6.5 (Mohs); Color: Tan, cream, or grey; Luster: Pearly to vitreous; Cleavage: Two directions at nearly 90 degrees; Structure: Triclinic or Monoclinic.
- Hardness
- 6-6
- Color
- Tan, cream, or grey
- Luster
- Pearly to vitreous
Identified More mineral →
Explore Feldspar (likely Orthoclase or Plagioclase) 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: Tan, cream, or grey; Luster: Pearly to vitreous; Cleavage: Two directions at nearly 90 degrees; Structure: Triclinic or Monoclinic.
Formation & geological history
Formed primarily in igneous rocks like granite or metamorphic rocks. The specimen appears water-worn (tumbled), likely found in a riverbed or coastal deposit, and is associated with the Piedmont province geology near Baltimore.
Uses & applications
Large scale feldspar is used in glassmaking and ceramics. Polished or unique specimens like moonstone or sunstone are used in jewelry.
Geological facts
Feldspar is the most abundant mineral group in Earth's crust, making up about 60% of terrestrial rocks. The name 'feldspar' is derived from the German 'Feldspat', meaning field mineral.
Field identification & locations
Identified by its distinctive blocky cleavage and pearly luster. In the Maryland Piedmont region, it is commonly found in weathered granite or gneiss outcrops and stream gravels.
More like this
Other mineral specimens
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Sandstone with Mineral Veining or Crust
Sedimentary Sandstone (mostly SiO2 with Fe2O3 tinting)
sedimentary
Schist
Schist
Metamorphic
Potassium Feldspar (Orthoclase)
Orthoclase (KAlSi3O8)
mineral
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic