Vesicular Basalt (Lava Rock)
Extrusive Igneous Rock (Mafic Basalt) · Mineral Specimen / Decorative Stone / Industrial Mineral
Crystal System
Amorphous for glass, Monoclinic/Triclinic/Orthorhombic for microcrystalline components; habit is vesicular and scoriaceous
Mineral Group
Silicates (Mafic group)
Chemical Formula
Complex mixture of Plagioclase Feldspar (CaAl2Si2O8/NaAlSi3O8) and Pyroxene ((Mg,Fe,Ca,Al,Ti)2Si2O6)
Formation Process
Igneous (extrusive volcanic); forms from the rapid cooling of mafic lava at the Earth's surface where trapped gases create holes (vesicles)
About This Crystal
A dark, dense, fine-grained rock with a porous or pitted surface. Color is typically grey to black, often weathering to brown or reddish-grey. It is opaque with a dull to sub-glassy luster.
Physical Characteristics
Color: Dark grey to charcoal; Streak: Grey to light brown; Cleavage: None (non-mineral rock); Fracture: Uneven to conchoidal (in glassier bits); Specific Gravity: 2.8 - 3.0; Magnetism: Often weakly magnetic due to magnetite inclusions.
Optical Properties
Opaque; No visible light transmission; Refractive index is not applicable for bulk rock, though component minerals are generally high (1.5–1.7).
Hardness & Durability
Origin Region
Volcanic regions globally (e.g., Iceland, Hawaii, Etna, Deccan Traps); found in oceanic crust and continental flood basalts
Hardness & Durability
Mohs hardness: 5.0 - 6.0; Durable and tough as a bulk material, though vesicular varieties can be brittle and crumble under high pressure.
Care & Maintenance
Wash with warm soapy water to remove dust from pores; generally resistant to chemicals and sunlight. Avoid dropping on hard surfaces which may chip the vesiculated edges.
Rarity & Value
Very Common; Low value as a mineral specimen. Most value is found in bulk industrial use (construction) or as decorative landscaping stone.
Special Characteristics
Highly vesicular texture (gas bubbles); can sometimes contain xenoliths or small inclusions of olivine (green) or feldspar (white).
Lore & History
Historically used for grindstones and early architecture (Roman roads). In modern folklore, it is often called a 'foundation stone' used for grounding and protection due to its volcanic origin from the Earth's core.