Concrete with Aggregate
Man-made Composite Material · Building Material / Decorative Stone (Urbanite)
Crystal System
Amorphous (matrix) with various crystal systems present in the gravel aggregates (Cubic, Hexagonal, etc.)
Mineral Group
Anthropogenic Material (Artificial stone-like composite)
Chemical Formula
Complex mixture: Primarily Ca2SiO4, Ca3SiO5 (Portland Cement) plus SiO2 and various silicates in aggregate
Formation Process
Industrial/Synthetic: Created through the hydration of Portland cement mixed with water, sand, and coarse mineral aggregates
About This Crystal
A coarse, clastic appearance featuring prominent dark gray and brown pebbles embedded in a porous, light gray-tan cementitious matrix. Shows visible air pockets (voids) and a rough, abrasive surface texture.
Physical Characteristics
Color: Mottled gray/tan with multicolored clasts; Streak: White to light gray; Cleavage: None; Fracture: Irregular/granular; SG: approx 2.4; Non-fluorescent usually.
Optical Properties
Opaque; Dull/Earthy luster; No significant birefringence or pleochroism in the matrix; clasts may show individual mineral properties.
Hardness & Durability
Origin Region
Found globally; typically sourced from construction sites, demolition debris, or riverbeds as urban runoff
Hardness & Durability
Variable: Matrix is approx 3-5 on Mohs scale; aggregate clasts (like quartz) can be up to 7. Brittle toughness; sensitive to acids.
Care & Maintenance
Wash with warm soapy water; avoid acidic cleaners (vinegar) which can dissolve the calcium-based binder; store in dry conditions.
Rarity & Value
Common/Abundant; negligible financial value as a mineral specimen; primarily discarded as construction waste.
Special Characteristics
Porous structure with vesicular-like voids; contains heterogenous rock fragments (phenocryst-like clasts) of varied mineralogy.
Lore & History
Historically represents the Industrial Age; symbolizes foundation and urban development. In modern 'urban mineralogy,' it is referred to as anthropocene rock.