Tiffany Stone (Bertrandite) Slabs
Bertrandite is more commonly called Tiffany Stone. It is an opalite
(common opal), and often has a soft rind. Fine quality tiffany stone
has purple coloration and can even be a pure dark, translucent purple
Tiffany Stone comes
from one locality in Utah. The mine is no longer open for collecting and all of
this beautiful material is now ground up for beryllium ore. The beryllium content
in tiffany stone is locked up in a silicated compound, much like the beryl minerals
aquamarine and emerald. Because of the compounded nature of the beryllium in these
minerals, it is like any other agate or opalite and not hazardous to cut and polish
. However, the dust from pure industrial beryllium, metallic alloys of beryllim
or ceramic beryllium is toxic and very dangerous to breathe.
Most opalites can contain some fractures, as does tiffany stone. Some uneven
hardness can be encountered in this material, but tiffany stone generally
cuts easily and takes a fine polish with diamond, tin or cerium oxide.
Mohs hardness is 5 to 6.
Example of Tiffany Stone Cabochons
Not cut from material below.