Description
Formula:
A(D3)G6(T6O18)(BO3)3X3Z
A = Ca, Na, K, or is vacant (large cations);
D = Al, Fe2+, Fe3+, Li, Mg2+, Mn2+ (intermediate to small cations – in valence balancing combinations when the A site is vacant);
G = Al, Cr3+, Fe3+, V3+ (small cations);
T = Si (and sometimes minor Al, B3+);
X = O and/or OH;
Z = F, O and/or OH.
System: Trigonal
Locality: Kaatiala, Perä-Seinäjoki, Southern Ostrobothnia, Finland
Habit: Euhedral crystals
Color: Purple
Luster: Vitreous luster
Weight: 241 g
Dimensions: 7.5 x 6.4 x 3.9 cm