Basalt Fragment
Extrusive Igneous Rock / Basalt · Mineral Specimen
Crystal System
Amorphous to Microcrystalline
Mineral Group
Silicates (primarily pyroxene, plagioclase feldspar, and olivine)
Chemical Formula
Complex silicate of Fe, Mg, Ca, Al, Na, Si, O
Formation Process
Igneous process formed by the rapid cooling of low-viscosity, magnesium- and iron-rich lava at or near the Earth's surface.
About This Crystal
Small, dark grey to black, fine-grained, opaque rock fragment with an irregular, weathered, and slightly vesicular surface texture and a dull to sub-vitreous luster.
Physical Characteristics
Color ranges from dark gray to black. Streak is grey to white. Habit is massive or aphanitic (fine-grained). Cleavage is absent. Fracture is uneven to conchoidal. Specific gravity is approximately 2.8 to 3.0. Tenacity is brittle. Non-magnetic to weakly magnetic depending on magnetite content.
Optical Properties
Opaque in hand specimen. Under petrographic microscope, shows minerals with double refraction (birefringence), interference colors, and lack of pleochroism in main mineral phases.
Hardness & Durability
Origin Region
Globally distributed in volcanic provinces, oceanic crust, and basaltic traps (e.g., Columbia River Basalt Group, Deccan Traps, Iceland, Hawaii)
Hardness & Durability
Mohs hardness typically 5 to 6 for the aggregate rock mass. Toughness is moderate to high due to fine-grained interlocking crystals, providing good resistance to impact.
Care & Maintenance
Standard cleaning with water and mild soap. Extremely durable and stable against environmental chemicals, heat, and light.
Rarity & Value
Common. Basalt is one of the most abundant rock types on Earth and planetary surfaces. Value is low, typically collected as a geological or educational specimen.
Special Characteristics
May contain tiny micro-phenocrysts of olivine or plagioclase, or small vesicles (gas cavities) filled with secondary minerals like zeolites or quartz.
Lore & History
Historically used by ancient civilizations for construction, grinding stones, tools, and sculptures (such as the Moai statues of Easter Island). In modern metaphysical practices, basalt (often as lava stone) is used for grounding, calming emotions, and root chakra balancing, though these are traditional beliefs rather than scientific claims.