Reference:
▪ Oberti, R., Boiocchi, M., Hawthorne, F.C., Ciriotti, M.E. (2018): Magnesio-hornblende from Lüderitz (Namibia): mineral description and crystal chemistry. Mineralogical Magazine, 82, 1253–1259.
Abstract:
Magnesio-hornblende (IMA-CNMNC vote 2017-059) has been characterised in a specimen collected in the sand dunes of Lüderitz, Karas Region, Namibia (~ 26°38′52″S; 15°09′28″E). The empirical formula derived from electron microprobe analysis and single-crystal structure refinement is A(0.73Na0.22K0.05)Σ=1.00 B(Ca1.79Fe2+0.10Mg0.04Mn2+0.03Na0.04)Σ=2.00 C(Mg3.48Fe2+0.97Al0.28Fe3+0.23Cr3+0.01Ti0.03)Σ=5.00 T(Si7.18Al0.82)Σ8.00 O22 W[(OH)1.93F0.05Cl0.02]Σ=2.00. Magnesio-hornblende is biaxial (-), with α = 1.640(2), β = 1.654(2), γ = 1.666(2) (measured with gel-filtered Na light, λ = 589.9 nm) and 2V (meas.) = 82(1)º, 2V (calc.) = 84.9°. The unit-cell parameters are a = 9.8308(7), b = 18.0659(11), c = 5.2968(4) Å, β = 104.771(6)°, V = 909.64 (11) Å3, Z = 2, space group C2/m. The strongest ten reflections in the X-ray powder pattern [d values (in Å), I, (hkl)] are: 2.709, 100, (151); 8.412, 74, (110); 3.121, 73, (310); 2.541, 58, (-202); 3.386, 49, (131); 2.596, 45, (061); 2.338, 41, (-351); 2.164, 39, (261), 2.941, 34, (221), 2.731, 31, (-331).
▪ Oberti, R., Boiocchi, M., Hawthorne, F.C., Ciriotti, M.E. (2018): Magnesio-hornblende from Lüderitz (Namibia): mineral description and crystal chemistry. Mineralogical Magazine, 82, 1253–1259.
Abstract:
Magnesio-hornblende (IMA-CNMNC vote 2017-059) has been characterised in a specimen collected in the sand dunes of Lüderitz, Karas Region, Namibia (~ 26°38′52″S; 15°09′28″E). The empirical formula derived from electron microprobe analysis and single-crystal structure refinement is A(0.73Na0.22K0.05)Σ=1.00 B(Ca1.79Fe2+0.10Mg0.04Mn2+0.03Na0.04)Σ=2.00 C(Mg3.48Fe2+0.97Al0.28Fe3+0.23Cr3+0.01Ti0.03)Σ=5.00 T(Si7.18Al0.82)Σ8.00 O22 W[(OH)1.93F0.05Cl0.02]Σ=2.00. Magnesio-hornblende is biaxial (-), with α = 1.640(2), β = 1.654(2), γ = 1.666(2) (measured with gel-filtered Na light, λ = 589.9 nm) and 2V (meas.) = 82(1)º, 2V (calc.) = 84.9°. The unit-cell parameters are a = 9.8308(7), b = 18.0659(11), c = 5.2968(4) Å, β = 104.771(6)°, V = 909.64 (11) Å3, Z = 2, space group C2/m. The strongest ten reflections in the X-ray powder pattern [d values (in Å), I, (hkl)] are: 2.709, 100, (151); 8.412, 74, (110); 3.121, 73, (310); 2.541, 58, (-202); 3.386, 49, (131); 2.596, 45, (061); 2.338, 41, (-351); 2.164, 39, (261), 2.941, 34, (221), 2.731, 31, (-331).