Granite Cobble
Granite Igneous Rock · Building Stone and Geological Specimen
Crystal System
Multicrystalline aggregate composed of various crystal systems including Trigonal (Quartz), Monoclinic/Triclinic (Feldspar), and Monoclinic (Mica). Habit is massive, granular rock.
Mineral Group
Silicates (Composite Rock)
Chemical Formula
Complex silicate rock primarily composed of SiO2 (Quartz), KAlSi3O8 (Alkali Feldspar), NaAlSi3O8 (Plagioclase), and K(Fe,Mg)3AlSi3O10(OH)2 (Biotite)
Formation Process
Igneous intrusive process, forming from the slow cooling and solidification of magma rich in silica and alkali elements deep beneath the Earth's crust.
About This Crystal
An irregularly shaped, weathered rock fragment embedded in soil and garden debris. The surface shows a speckled, pinkish-gray coloration with visible mineral grains and patches of green biological growth like moss or algae.
Physical Characteristics
Color ranges from pink and gray to white with black flecks. Streak is white. Fracture is uneven to conchoidal. Specific gravity averages around 2.65 to 2.75. Tenacity is tough and brittle.
Optical Properties
Varies by individual mineral component. Quartz shows uniaxial positive optical properties with no cleavage, while feldspars show biaxial properties and distinct cleavage planes.
Hardness & Durability
Origin Region
Found globally in continental crust, commonly used as glacial erratics, river rocks, or landscaping stones
Hardness & Durability
Overall Mohs hardness is approximately 6 to 7 due to the dominance of quartz and feldspar. High durability, excellent resistance to weathering, wear, and abrasion.
Care & Maintenance
Can be washed with water and a soft brush to remove dirt, moss, or organic debris. Extremely durable and impervious to normal environmental conditions.
Rarity & Value
Extremely common. Granite is one of the most abundant intrusive rocks on Earth and holds little value as a mineral specimen unless part of a specific architectural or decorative application.
Special Characteristics
Composed of interlocking mineral crystals that give it high compressive strength and a characteristic salt-and-pepper or pink-speckled appearance.
Lore & History
Historically used extensively in ancient architecture, monuments, and sculpture due to its incredible durability. In modern crystal lore, granite is sometimes associated with grounding energy, strength, and stability, though it is primarily recognized as a fundamental geological formation rather than a traditional metaphysical crystal.