For other uses, see Zechariah. The male given name Zechariah is derived from the Hebrew ×Ö°×Ö·×¨Ö°×Ö¸×, meaning The Lord has remembered.. It has been translated into English in many variant forms and spellings, including Zachariah, Zacharias and Zachary. It was the name of various men in the Bible.
Double Refraction in Minerals Double refraction is the splitting of a single ray of light into two refracted rays when passing through an anisotropic mineral. All anisotropic minerals exhibit double refraction. Double refraction can be practically observed by placing a transparent Calcite (Iceland spar) crystal on a sheet of paper with a black dot on it. When the dot is viewed through the crystal, two dots are seen.
Relief is a useful distinguishing property for the the igneous rock-froming minerals; all the mafic minerals show high relief but all the felsic minerals (with the exception of muscovite) show low relief.he instrument we use to look at thin sections is a polarising microscope. These are expensive (1500!) items and also need to be treated with care, especially the lenses. Before using a polarising microscope it is important to know a bit about polarised light and the optical properties of minerals.