Conway granite

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Conway granite is a typically pink mineral-rich igneous (or mesoperthitic) biotite granite.[1] It is amphibole-free and of coarse particle size (with portions of the rock fine-grained or porphyritic).[1]

Conway granite has a relatively high concentration of thorium, at about 56 (±6) PPM; this amount is not enough to make the granite dangerously radioactive, but it is sufficient to make the rock a low-grade (almost certainly not economic, at least in the early years) source of thorium for a thorium fuel cycle.[2]

Geologist Edward Hitchcock named the granite in 1877 after the town of Conway, New Hampshire, which is near where it is mined.[3] The Old Man of the Mountain, a famous geologic feature in New Hampshire (which collapsed in 2003) was made of Conway granite.[4]



  • Hutchinson, Robert; Johnson, William; and Hamilton, Dick. The Old Man of the Mountain. San Francisco: Browntrout Publishers, 2003.
  • Billings, Marland P. and Williams, Charles R. Geology of the Franconia Quadrangle, New Hampshire. Concord, N.H.: State Planning and Development Commission, 1935.