Colour of Sphalerite

The colour of sphalerite is white nearly colourless when pure, whereas sphalerite with high Fe content is almost black in colour. Besides a minor amount of cadmium and manganese is contained in addition to iron. The present writer has carried out some quantitative studies on the colour of sphalerite, especially in connection between the chemical components and whiteness. The whiteness in colour of sphalerite in which Fe ion substituting for Zn ion, decreases from 72% to 12% straightly, as the Fe content increases from 0% to 15%

Whiteness in Colour of Talc

Whiteness in colour of talc is one of the most useful property in commercial uses, and it is used in ceramics and as a filler in paint, paper, and rubber. The present writer has carried out some quantitative studies on the whiteness as one of physical properties with the automatic photo-electric spectrometer. Consequently, whiteness value being calculated by the Hunter equation amounts to 88.9% for the maximum. In general, however, the talc contains the other minerals as impurities, therefore the whiteness in colour of talc decreases from 88.9% to 72.3% with the increase of impurities

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+