How to Identify Quartzite: What to Look For and Home Tests

Metamorphic rocks were changed by heat and pressure. Look for a sugary or platy texture, minerals lined up in one direction, and a hardness or ring that the parent rock did not have. The properties that identify Quartzite — luster: Fracture surfaces can be smooth or even glassy, like quartz; cleavage or fracture: Quartz grains are so tightly interlocked that individual grains are hard to distinguish; conchoidal fracture cuts straight through both grains and cement. For a rock, texture and grain size matter more than any single hardness number.

• Hardness test: quartzite is extremely hard and resistant — a knife cannot scratch it.

• [Sandstone](/lookup/rocks-and-minerals/sandstone): Quartzite is metamorphic; its fracture cuts straight through the grains (smooth/glassy). Sandstone fractures along grain boundaries (granular appearance).

Photograph a fresh, unweathered surface in daylight, then a second shot of any crystal faces or broken edge. Include a coin for scale. If you did a streak test, photograph the streak next to the specimen. The app suggests the likely mineral or rock; confirm with hardness and the tests above before you label it.

Quartzite was originally quartz sandstone, recrystallized through metamorphism ('QUARTZITE is a metamorphic rock that originally was quartz sandstone,' same source as above).