Lava Rock with Augite crystals
Basalt with Augite (IMA-approved: Augite) · Mineral Specimen / Igneous Rock Component
Crystal System
Monoclinic; typically occurs as short, prismatic crystals with a square or octagonal cross-section in volcanic matrix.
Mineral Group
Silicates (Inosilicates) - Pyroxene Group
Chemical Formula
(Ca,Mg,Fe)2(Si,Al)2O6
Formation Process
Igneous/Magmatic; formed from the rapid cooling of magnesium and iron-rich lava (basaltic) at or near the Earth's surface.
About This Crystal
The specimen consists of dark, scoriaceous volcanic matrix (lava rock) containing small, embedded black to dark brownish-green crystals of Augite. The matrix is vesicular (porous) and opaque with a dull, earthy luster, while the Augite crystals exhibit a vitreous to resinous luster and appear nearly opaque in thick sections.
Physical Characteristics
Color: Black, dark green, or brown; Streak: Greenish-gray; Cleavage: Two distinct directions meeting at nearly 90 degrees; Fracture: Conchoidal to uneven; Specific Gravity: 3.2 - 3.6; Fluorescence: Generally none.
Optical Properties
Biaxial (+); Refractive Index: 1.671 - 1.735; Birefringence: 0.018 - 0.033; Pleochroism: Weak (shades of green and brown); Optically doubly refractive.
Hardness & Durability
Origin Region
Globally distributed; notable sources include Mount Vesuvius (Italy), volcanic regions of Iceland, Hawaii (USA), and the Eifel region (Germany).
Hardness & Durability
Mohs Hardness: 5.5 to 6.0. The basaltic matrix is brittle and porous, while the Augite crystals are relatively durable but prone to cleavage planes.
Care & Maintenance
Clean with warm soapy water and a soft brush to remove dust from pores. Avoid ultrasonic cleaners as the porous matrix may trap liquids or shatter. Protect from hard impacts due to the brittle nature of the scoria.
Rarity & Value
Common; primarily valued as a geological specimen or for educational purposes rather than as a gemstone. Not typically treated.
Special Characteristics
Presents a vesicular texture (gas bubbles trapped during cooling). The crystals show characteristic pyroxene cleavage and are primary rock-forming minerals in mafic igneous rocks.
Lore & History
Historically used as a building material and for road metal. In metaphysical traditions, lava rock is associated with the Root Chakra and is believed to symbolize strength, courage, and grounding energy during times of change.