Pezzottaite

With the exception of hardness (8 on Mohs scale), the physical and optical properties of pezzottaite—i.e., specific gravity 3.10 (average), refractive index 1.601 to 1.620, birefringence 0.008 to 0.011 (uniaxial negative)—are all higher than typical beryl. Pezzottiate is brittle with a conchoidal to irregular fracture, and streaks white. Like beryl, it has an imperfect to fair basal cleavage. Pleochroism is moderate, from pink-orange or purplish pink to pinkish purple. Pezzottaite's absorption spectrum, as seen by a hand-held (direct vision) spectroscope, features a band at 485–500 nm with some specimens showing additional weak lines at 465 and 477 nm and a weak band at 550 to 580 nm.