Knapp Prospect, Canton, Hartford County, Connecticut, USAi

Regional Level Types
Knapp Prospect	Prospect
Canton	Town
Hartford County	County
Connecticut	State
USA	Country

The Knapp prospect lies in the town of Canton 3 miles N. 30° W. of Canton village. It may be approached from Canton by traveling 3.5 miles west on U. S. Highway 44 to its junction with an asphalt road leading northward. Proceed on this road 1.1 miles to a dirt road which leads 0.4 mile to the prospect. The only working (fig. 123) is an irregular opencut 65 feet long, ½ to 4 feet deep, and about 25 feet wide, blasted into the side of a pegmatite knoll. Most of the cut is covered with back fill. The prospect was mapped by V. E. Shainin in March 1944. The exposed part of the pegmatite appears to be dome-shaped. It is at least 280 feet long and has an exposed thickness of 8 feet; its actual thickness is probably considerably greater. The wall rock is a medium-grained garnet-rich quartz-muscovite-biotite schist that is visible only where it overlies the pegmatite. At the southwestern end of the prospect the contact strikes N. 70° E. and dips 20° SE. Much of the wall rock that covered the southern part of the pegmatite has been eroded, so that the contact surface is exposed. In the northeastern part of the prospect, where erosion has cut more deeply into the pegmatite, the hanging-wall contact strikes approximately N. 25° E. and dips about 20° SE. At the top of the knoll, north of the opencut, the schist has also been removed by erosion. The contact there was almost horizontal. Probably some irregular patches of schist visible in the pegmatite are xenoliths and others are remnants of the overlying schist wall.

In the face of the opencut, where the pegmatite is best exposed, the following zones, from the wall inward, are present:

1. Border zone, 1 to 4 inches thick. Consists of fine-grained quartz, muscovite and plagioclase with accessory garnet and tourmaline. Milky and smoky quartz are common.
2. Quartz-muscovite zone, 6 inches to 1½ feet thick. Consists of coarse quartz and muscovite, medium-grained plagioclase and accessory fine-grained garnet. Quartz, much of it smoky, constitutes well over 50 percent of the unit. Rock mined from the zone has yielded 10 percent mine-run mica.
3. Quartz-perthite zone, minimum thickness 3 feet. Only the upper portion of this zone is exposed; it consists of coarse anhedral quartz and subhedral perthite, with accessory scrap muscovite.

Northeast of the opencut the quartz-perthite zone is not visible. Pegmatite underlying the quartz-muscovite zone there consists of medium-grained quartz, plagioclase and muscovite, subordinate amounts of perthite and accessory garnet and tourmaline. This unit has an exposed thickness of 2 feet. Its contact with the quartz-perthite zone is concealed by overburden.

The mica deposit is of the wall-zone type. The mica forms pale ruby books that range from 1 to 8 inches in breadth and average 3 inches in diameter. Most of the books are clay-stained, wedged, and reeved, and some show “A” structure, cross-fracturing, and ruling. The mica is hard but not flat. The percentage of sheet recovered from crude mica was low, largely because of the wedge shape of the books.

Assuming an average thickness of 1 foot for the quartz-muscovite zone, and a yield of 10 percent mine-run mica from the zone, indicated reserve of recoverable crude mica within the area of the geological map is estimated to be 50 tons. However, as probably not more than 1 percent of sheet mica could be recovered from the mine-run product, the prospect is not promising.