Study of the System CaMgSi2O6-CaFe^[3+]AlSiO6-CaAl2SiO6-CaTiAl2O6 : III. The Join CaMgSi2O6-CaFe^[3+]AlSiO6-CaTiAl2O6 at 1 atm

The join CaMgSi2O6-CaFe^[3+]AlSiO6-CaTiAl2O6 was studied in air at 1 atm by the ordinary quenching method. Clinopyroxene(ss), forsterite, perovskite, magnetite(ss), spinel(ss), anorthite, melilite, unknown phase X and hibonite were encountered. Phase X was analysed by EPMA. At liquidus temperatures the following assemblages are confirmed: clinopyroxene(ss) + forsterite + spinel(ss) + liquid, clinopyroxene(ss) + magnetite(ss) + spinel(ss) + liquid, forsterite + perovskite + spinel(ss) + liquid, and magnetite(ss) + spinel(ss) + phase X + liquid. At subsolidus temperatures clinopyroxene(ss) single phase field extends up to 18 wt.% CaTiAl2O6, showing that the content of TiO2 in clinopyroxene(ss) increases with increasing CaFe3+ AlSiO6. Following phase assemblages were confirmed in the subsolidus regions: clinopyroxene(ss) + perovskite, clinopyroxene(ss) + perovskite + spinel(ss), clinopyroxene(ss) + perovskite + melilite (+ anorthite), clinopyroxene(ss) + perovskite + spinel(ss) + melilite + anorthite, clinopyroxene(ss) + perovskite + anorthite + spinel(ss), and clinopyroxene(ss) + perovskite + hibonite + anorthite. Even in the field of clinopyroxene(ss) + perovskite, TiO2 content in clinopyroxene(ss) continues to increase and attains up to 9.20% TiO2 and 18.57% Al2O3. An implication of the join to Ti-rich fassaitic pyroxene from the alkalic rocks is discussed

Inesite from the Kokuriki Mine, Hokkaido, Japan

Inesite occurs in veinlet cutting hematite ore from the Kokuriki mine, eastern Hokkaido. Its associated minerals are rhodochrosite, barite and quartz. The inesite forms fine prisms up to 1 mm long and is pale orange in color. Refractive indices are: α=1.618(3), β=1.639(3) and γ=1.656(3). Biaxial, negative. 2V(meas.)=67-70°. The composition is as follows: SiO2 45.94, Al2O3 0.02, Fe2O3 0.57, MnO 37.50, MgO 0.10, CaO 8.60, Na2O 0.04, K2O 0.04, H2O 8.90, Total 101.71 wt.%. The H2O content was determined by a thermogravimetric analysis. The empirical formula is calculated as: (Ca1.97Na0.02K0.01)Σ2.00(Mn6.80Mg0.03) Σ6.83-(Si9.84Fe3+0.09Al0.01)Σ9.94O35.00H12.72. Unit-cell parameters based on morphological cell were determined by X-ray powder diffraction as follows: a=8.938(4), b=9.259(5), c=11.959(5)Å, a=91.96(7)°, β=132.72(3)°, γ=94.36(6)°. Crystal field spectra indicate that the orange color of the inesite may be caused by Mn3+ converted from a part of Mn2+