The cell parameters, optical properties and chemical composition of 103 samples in the tremolite-actinolite-ferro-actinolite series have been measured. The combination of properties and the large number of samples provided a powerful means of determining systematic relationships in the series. The cell parameters and refractive indices for end members tremolite and ferro-actinolite were determined by regressions of the data. Natural tremolite is not systematically enriched in cummingtonite and/or depleted in Ca. The substitution of Al for Si involves, on average, a tschermakite component. Samples characterized as asbestos have lower Al concentrations than massive or byssolite samples. There is a discontinuity in [alpha] between 10% & 12% ferro-actinolite. There are also indications of discontinuities in optical properties and [-] between 26% and 32% ferro-actinolite that may be due to an increase in tschermakite substitution.
Citation: American Mineralogist
Issue: No. 9
Pub Type: Journals
actinolite, amphibole, asbestos, refractive index, tremolite, x-ray diffraction