Basalt with Quartz Veins

Hardness 5-6 (basalt), 7 (quartz). Dark gray to black color, fine-grained matrix with lighter, intersecting quartz veins. Dull to slightly shiny luster where water-worn.

Formed from the rapid cooling of basaltic lava at or near the surface. Later, silica-rich fluids permeated cracks in the basalt, depositing quartz veins. Rounded shape indicates it was likely transported and smoothed by water action, possibly in a river or on a beach.

Common rock used for landscaping, road base, and construction material. As a specimen, it is often kept by casual collectors for its aesthetic patterns.

Basalt is the most common volcanic rock type on Earth and forms the oceanic crust. The presence of intersecting veins is a classic example of secondary mineralization filling fractures in a host rock.

Easily identified by its dark, fine-grained matrix contrasting with lighter, harder veins. Commonly found in areas with past volcanic activity or downstream in riverbeds draining such areas.