The absorption spectra of aragonite and strontianite in the near infra-red

Abstract

In a series of papers dealing with some theoretical determinations of carbonate crystals, Chapman and his collaborators (1) have discussed a number of properties in calcite and magnesite, while later on they extend their work to the carbonates of zinc, iron, manganese and cadmium. They arrive at the general result that throughout the uni-axial series examined by them the CO 3 group remains almost unchanged in size. Their calculations yield a set of unique values for the rhombohedral angle, for which the limits are 101° 55' (calcite), and 103° 28' (calamine). In a similar way, the extremes in the size of the rhombohedral cell are shown by calcite and magnesite. Unfortunately these investigations have not yet embraced the bi-axial carbonates. On the experimental side, Schaefer and his school (2) have recently concluded a systematic study of the absorption spectra of the uni-axial crystals calcite, magnesite, dolomite, chalybite, and of the bi-axial crystals witherite and cerussite between the wave-lengths 1 and 23μ, accessible with prisms of quartz, fluorite, rock-salt and sylvite.