"The granite consisted chiefly of albite, quartz, muscovite, microperthite, fluorite, and topaz; zircon was very rare. The low to high quartz transition enhanced thermal expansion and porosity. Heating was continued step-wise to 1,300 degrees C. and caused an irreversible increase in porosity at all temperatures investigated. . . . Fluorite began to melt against muscovite or alkali-feldspar between 800 degrees and 900 degrees C. Muscovite developed brownish pleochroism at the lower, and was replaced by mullite at the higher, temperatures. The gradual melting of feldspar, the development of cleavages and cracks in quartz, and the invasion of these cracks by feldspathic glass resembled phenomena in certain xenoliths." A new chemical analysis and a mode are given for the granite used.