Tacharanite

General Information:
 Chemical Formula:
Ca12Al2Si18O33(OH)36
 Composition:
(Molecular Weight = 2,180.68 gm)
Calcium 22.05 % Ca
Aluminum 2.47 % Al
Silicon 23.18 % Si
Hydrogen 1.66 % H 
Oxygen 50.62 % O 
 Empirical Formula:
Ca12Al2Si18O33(OH)36
 Environment:
In vesicles or fracutes in dolorites or other basic igneous rocks.
 IMA Status:
Approved IMA 1961
 Locality:
Portree, Isle of Skye, Scotland.
 Name Origin:
Named from the Gaelic "tacharan," a changeling, because on standing in air the mineral breaks down to form other compounds (not noticed by later investigators).
Physical Properties:
 Color:
white.
 Density:
2.21 - 2.36, Average = 2.28
 Habits:
Cryptocrystalline - Occurs as crystals too small to distinguish with the naked eye., ,
 Hardness:
5 - Apatite
 Luster:
Earthy (Dull)
 Streak:
white
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