However, several characteristics distinguish pyrite from actual gold. Pyrite ranks 6 to 6.5 on the Mohs hardness scale, making it significantly harder than gold, which measures only 2.5 to 3. Pyrite is also brittle and will shatter when struck, while gold is malleable. Additionally, pyrite's specific gravity (approximately 5.0) is considerably lower than gold's (19.3), making it much lighter for its size.
Large raw specimens often display a fascinating array of crystal habits. Some form as perfect cubes with mirror-like faces, while others develop as interpenetrating crystals creating complex geometric patterns. Particularly impressive are massive clusters where numerous individual crystals have grown together, creating stunning natural sculptures that can weigh several pounds or even kilograms.
The surface of raw pyrite frequently exhibits a beautiful iridescent tarnish, displaying rainbow hues of blue, purple, and gold. This tarnish, resulting from oxidation, adds to the stone's visual appeal and is considered desirable by many collectors, as it demonstrates the specimen's authenticity and natural state.