Hi
I have some very fine facettable thaumasite crystals. But
before cutting them, I need to know on:
1. Refractive index
2. Density
3. Cleavage planes
4. Heat sensitivity
5. Brittleness
6. Polishing compounds
If anyone can give me these (or some of these) ?
Thanks a lot
Claude Marc-Aurle
Lapilia
E-Mail : lapilia@vipxlnet.com
WebSite : http://www.vipxlnet.com/lapilia/accueila.htm
CP 48507, Outremont Postal Outlet, Qubec, Canada H2V 4T3
Gemstones from all around the world
Claude,
Thaumasite is Hydrated Calcium Silicon Carbonate Sulfate
Hydroxide. The crystals are usually colorless and translucent.
If you’ve got transparent rough…wow! 
Luster is vitreous, hardness is 3.5, specific gravity is 1.9
(very low density), cleavage is poor, fracture is uneven, streak
is white. I’m not sure of the refractive index. I wouldn’t
recommend cutting it for jewelry use because of the softness -
but it would be an interesting collector’s stone.
-Pete-
Buffalo, NY
Color is colorless or white.
Luster is vitreous.
Transparency: Crystals are translucent.
Crystal System is trigonal; bar 3 2/m.
Crystal Habits include acicular crystals and massive forms.
Cleavage is poor and rarely seen.
Fracture is uneven.
Hardness is 3.5
Specific Gravity is approximately 1.9 (well below average)
Streak is white.