AUGITE is a dark brown to black pyroxene which occurs between the mosaic of whitish labradorite feldspar prisms in the weathered diabase near the Mount Holyoke House. AMPHIBOLE crystals are dark green to black, “match-shaped” crystals. They have almost the same hardness as a knife and are characterized by two cleavages parallel to their length and intersecting at 56°. The mineral is also abundant in metamorphic rocks and is frequently reported as a “fossil fern” from ledges at Charlemont and Shelburne Falls. _Minerals of Metamorphic Rocks_ The principal minerals of metamorphic rocks include many which are likewise present in pegmatites and igneous rocks, such as microcline, albite, quartz, muscovite, biotite, amphibole, serpentine and tourmaline. But there are others which are more exclusively metamorphic: GARNET occurs in twelve- or twenty-four-sided red crystals. It is much harder than a knife. The geometric form is diagnostic, and crystals up to an inch thick are obtainable in Plainfield, Massachusetts, and at Grafton, Chester, and Gassetts in Vermont. They occur in a muscovite schist, in which the muscovite flakes are wrapped around the individual crystals. TALC is a white to pale-green mineral found around the margins of intrusive rocks that are rich in olivine and serpentine. It is foliated and is so soft that even solid masses will rub off on cloth. It is present in the green marble quarry near Westfield. KYANITE is a sky-blue, bladed mineral, with two excellent cleavages at nearly 90°, and a good smooth fracture at almost 90° to both. One face is harder than a knife and the other two are softer. It is very abundant in the country rock southeast of the Westfield marble quarry. _The Minerals of Soils and Rock Decay_ Aluminous minerals decay to KAOLINITE, and those with a high iron content alter to LIMONITE. Both these products of decomposition form a sticky paste in their original forms. Kaolinite is white to yellow, and limonite or ochre is yellow to orange. Limonite also appears in orange-colored or brown balls, in icicle-like masses, and in thin beds. Specimens have approximately the hardness of a knife. Quartz does not decay easily and remains behind in solid granules. _The Minerals of Sedimentary Rocks_ Most sedimentary rocks are formed by the cementation of deposits of transported waste, derived from older materials. They may contain anything. The minerals which undergo rapid decay break down to limonite, kaolinite and quartz, leaving only the more resistant varieties, which include, in order of decreasing resistance, quartz, microcline, orthoclase, albite and muscovite. Less abundant constituents are garnet, tourmaline, zircon and magnetite.