One of my friends asked me back in December what I knew about a recently discovered red beryl (bixbite) deposit found in 2003 in Madagascar. He showed me a pinkish-purplish oval faceted stone that he claimed was the new bixbite material. Stop…right now… sorry for those who hate spoilers early on, but there is NO red beryl found in Madagascar…. NONE! I would like to take this moment to thank Chuck Henley for providing clear insight into this matter.
The material referred to incorrectly as bixbite is in fact a new mineral altogether! Discovered in 2003 in Madagascar is a cesium rich analog of beryl, the key word being analog.The chemical formula for the material discovered is Cs(Be2Li)Al2Si6O18. The material has been named pezzottaite, after Italian mineralogist Federico Pezzottaite. At first this material was thought to be bixbite or either a new variety of beryl, both of which are false. The determining factors for this are a) the fact that pezzottaite crystallizes in a trigonal system rather than a hexagonal system as all beryls do; and b) pezzottaite contains lithium. As we all know, the other beryls that contain lithium are… oh wait… there are none. The specific gravity of pezzottaite is much higher than that of various beryls: 3.10 vs. 2.63-2.80 (varies with species). The refractive index of pezzottaite is higher, 1.60-1.62 as compared to 1.56-1.60 for beryls (varies with species).
On the note of red beryl, let us first look at its chemical formula: Be3(Al,Mn)2Si6O18. Named after Utah mineral collector Maynard Bixby, it is agreed upon worldwide that this material is among the rarest of the rare when it comes to minerals, and the gem grade material is supercostly and almost always tends to be small when it comes to this material, as cut gems average around 0.15-0.20 cts.
Red Beryl on Rhyolitic Matrix
[...] higher, 1. 60-1. 62 as compared to 1. 56-1. 60 for beryls (varies with species)…. source: Bixbite vs. Pezzottaite: The Madagascar Connection?, Palmetto [...]