Graphite-veined Quartzite

Hardness: 7 (Mohs scale), Color: Off-white/tan matrix with black chaotic veining, Luster: Dull to vitreous, Structure: Granular/Microcrystalline, Specific Gravity: 2.6 - 2.8.

Formed from the regional metamorphism of quartz-rich sandstone. The dark veins are usually carbon-rich organic matter or hydrothermal mineral fluids that were squeezed into fractures under high pressure and temperature during the rock's formation, later being smoothed by water erosion.

Primarily used as decorative river rock, landscaping material, or a cabinet specimen for amateur geology collections. High-purity quartzite is used in glass making and industrial abrasives.

The 'web' or 'lightning' pattern on this specimen is a result of hydrothermal fracturing. Hot fluids circulate through cracks in the rock, depositing darker minerals (like graphite or chlorite) before the fractures seal shut and the entire mass is eroded into a smooth cobble.

Identify in the field by its extreme hardness (cannot be scratched by a steel knife) and the way the dark lines represent healed internal fractures rather than surface scratches. Found frequently in glacial till or riverbeds in the Northern Hemisphere.