Brown and Mottled Rocks (Fieldstone)
Silicate-rich Sedimentary/Metamorphic Aggregate · Mineral Specimen / Common Landscape Stone
Crystal System
Amorphous to Microcrystalline (Massive habit); no visible crystals
Mineral Group
Silicates (Tectosilicates / Phyllosilicates)
Chemical Formula
Predominantly SiO2 with traces of Fe2O3 and Al2Si2O5(OH)4
Formation Process
Sedimentary erosion and weathering; deposited through alluvial or glacial action
About This Crystal
Small, rounded to sub-angular terrestrial stones. Opaque with a dull, earthy luster and mottled brown to grey surface coloration due to iron oxide staining and organic debris.
Physical Characteristics
Boulders/pebbles with rounded edges, earthy brown streak, no discernible cleavage, uneven fracture, 2.6-2.7 specific gravity, non-fluorescent.
Optical Properties
Opaque; non-refractive in massive form; no visible pleochroism or phenomena.
Hardness & Durability
Origin Region
Ubiquitous; likely temperate North American soil profile (O-A horizon)
Hardness & Durability
Approx. 6-7 on Mohs scale (Quartz-based common stones); high durability and stability; subject to mechanical weathering.
Care & Maintenance
Requires no special cleaning; can be washed with water. Resistant to sunlight and common outdoor chemicals.
Rarity & Value
Common; very low market value for individual specimens. Primarily used for landscaping or as fill dirt.
Special Characteristics
None; lacks optical phenomena like chatoyancy or asterism.
Lore & History
Historically used for early stone tool construction (dry masonry walls). Symbolically associated with 'grounding' or 'earth element' in various folk traditions.