Basalt
Basalt (Igneous Rock) · Mineral Specimen / Industrial Rock
Crystal System
Microcrystalline to cryptocrystalline, aphanitic, massive habit
Mineral Group
Silicates (igneous rock composed mainly of plagioclase feldspar and pyroxene)
Chemical Formula
Complex silicate mixture containing SiO2, Al2O3, FeO, MgO, CaO, Na2O
Formation Process
Extrusive igneous formation via rapid cooling of mafic lava flows at or near the Earth's surface
About This Crystal
Fine-grained, dark gray to black rock with a dull to sub-vitreous luster, often showing vesicular texture from trapped gas bubbles during cooling, opaque and dense
Physical Characteristics
Dark gray to black color, white to gray streak, uneven or conchoidal fracture, no distinct cleavage, specific gravity around 2.8 to 3.0, brittle tenacity, non-magnetic generally though may contain minor magnetite
Optical Properties
Opaque in hand specimen, isotropic to anisotropic under petrographic microscope due to microscopic mineral constituents
Hardness & Durability
Origin Region
Found globally in oceanic crust, volcanic islands, and continental flood basalt provinces such as the Deccan Traps and Columbia River Basalt Group
Hardness & Durability
Mohs hardness typically 6 for the constituent minerals, high toughness and durability
Care & Maintenance
Standard cleaning with water and mild detergent, extremely durable with high resistance to chemical and weathering degradation
Rarity & Value
Extremely common worldwide, low economic value per weight, primarily used in construction and aggregate
Special Characteristics
Frequently exhibits vesicular, amygdaloidal, or porphyritic textures with phenocrysts of olivine, pyroxene, or plagioclase
Lore & History
Used historically by ancient civilizations for stone tools, grinding stones, and statues due to its durability; in modern metaphysical practices, it is associated with grounding and deep connection to the Earth