Pezzottaite Gemstones
New gemstones varieties are still being discovered. A good example is Pezzottaite, one of the most recent discoveries, recognized by the the International Mineralogical Association as a distinct variety only in September 2003.
Specimens of the new mineral were first thought to be red beryl (bixbite) or a cesium-rich variety of beryl. But unlike other beryls, the new mineral also contains lithium. It also crystallizes in the trigonal crystal system, unlike the other beryls which have hexagonal crystals.
Pezzottaite Rough from Madagascar
Pezzottaite was named in honor of the young Italian mineralogist, Federico Pezzotta, now curator of mineralogy at the Museo Civico di Storia Naturale in Milan.
The first specimens of pezzottaite were discovered in the granitic pegmatites of Fianarantsoa province in southern Madagascar. The small crystals ranged in color from orange-red to pink to raspberry red. Like morganite and bixbite, pezzottaite is believed to owe its color to radiation-induced color centers involving trivalent manganese. Most pezzottaite specimens from Madagascar are heavily included and cut gems rarely exceed 1 carat. Some specimens display chatoyancy (the cat's eye effect).
Faceted Pezzottaite
Pezzottaite has a similar hardness to beryl -- 8 on the Mohs scale. But its specific gravity (3.10) and refractive index (1.601 to 1.620) are both higher than beryl.
The Madagascar deposits of pezzottaite are now believed to be exhausted. However, a new deposit has since been found in Afghanistan. At first it was believed to be cesium-rich morganite, but analysis has shown it to be pezzottaite.
Both red beryl (bixbite) and pezzottaite are very rare gems. But red beryl is the more valuable of the two, probably because of its more saturated color. Apparently some specimens of pezzottaite have been offered on the market as red beryl, perhaps out of ignorance or perhaps with a fraudulent motive. Buyers of red beryl should take care that specimens are certified by a recognized gemological laboratory. |
