Garnetiferous Quartzite (Garnet Gneiss Pebble)

Physical Properties

Hardness: 6.5-7.5 (Mohs scale), Color: Pinkish-red (garnets) on a tan or grey base, Luster: Vitreous to dull, Crystal Structure: Granular/Granoblastic, Specific Gravity: 2.7-4.1 depending on garnet concentration

Formation & Geological History

Formed through high-pressure and high-temperature regional metamorphism of sandstone or granitic rock. Often found as water-worn pebbles in glacial till or riverbeds.

Uses & Applications

Mainly used as decorative stones, landscaping, or as a source of abrasive garnet industrial minerals.

Geological Facts

The red spots are typically almandine garnets. These rocks are often called 'watermelon rocks' or 'speckled stones' by beachcombers due to their distinct spotted appearance.

Field Identification & Locations

Identify in the field by the hard, rounded pink or red crystals embedded in a lighter, harder quartz-rich matrix; commonly found on Northern American and European beaches.

Identified on: 5/3/2026

Mode: Standard