Slate, also a metamorphic rock, is quarried in southwestern Vermont. Slate is a very fine-grained rock composed mainly of quartz and mica. Vermont slates formed about 475 million years ago during the Taconic Orogeny, a period of mountain building. When sedimentary rocks, such as shales or siltstones are metamorphosed, they become slate. Slate is on the roof of the Vermont State House.
Slate is used for flooring and as crushed product.
Granite, an igneous rock, occurs as small to large plutons in eastern Vermont. Most granite in Vermont is part of the New Hampshire Plutonic Series and is Devonian in age, making it quite a bit younger than the slates and marble of western Vermont. The granite from Barre is world famous for its use as monument stone. For more information on rocks in Vermont we recommend you visit Rock of Ages Homepage , Slate Valley Museum Homepage , USGS Interactive Quarry location map and USGS Mineral Industry Survey Site . For information and educational resources concerning minerals we recommend you visit the Mineral Information Institute .