Material name Feldspar
Composition (K0.59Na0.22Ba0.19)Al1.13Fe0.05Si2.82O8
Chemical formula weight 294.70
System Monoclinic
Temperature (ºC) r.t.
a (Å), b (Å), c (Å) 8.516(1) 13.023(2) 7.206(1) @
α (deg), β (deg), γ (deg) 90 115.90(5) 90 @
Unit cell volume (Å3) 718.9
Calculated density (g/p3) 2.72
Z 4
Space group C2/m (No.12)
atom site g x/a y/b z/c B2)
K 4i 0.59 0.2826(1) 0 0.1345(1) 1.94(2)
Na 4i 0.22 0.2826(1) 0 0.1345(1) 1.94(2)
Ba 4i 0.19 0.2826(1) 0 0.1345(1) 1.94(2)
Si1 8j 0.705 0.0087(1) 0.1831(1) 0.2240(1) 0.95(2)
Al1 8j 0.2825 0.0087(1) 0.1831(1) 0.2240(1) 0.95(2)
Fe1 8j 0.0125 0.0087(1) 0.1831(1) 0.2240(1) 0.95(2)
Si2 8j 0.705 0.7046(1) 0.1175(1) 0.3445(1) 0.95(2)
Al2 8j 0.2825 0.7046(1) 0.1175(1) 0.3445(1) 0.95(2)
Fe2 8j 0.0125 0.7046(1) 0.1175(1) 0.3445(1) 0.95(2)
O1 4g 1 0 0.1429(2) 0 1.80(6)
O2 4i 1 0.6273(4) 0 0.2864(4) 1.80(6)
O3 8j 1 0.8260(3) 0.1422(2) 0.2270(3) 2.08(5)
O4 8j 1 0.0308(3) 0.3101(2) 0.2567(3) 1.71(5)
O5 8j 1 0.1841(3) 0.1254(2) 0.4045(3) 1.70(5)

Reference: K. Viswanathan and K. Brandt, American Mineralogist, 65, 472 (1980).