Home Tour Physics Chemistry Earth Science Environment Scams Lesson Plans
Introduction Mapping Local Geology Regional Geology


Previous The Rock Next
Photograph of the intrusive rock at the top of Mt. Davidson

This image is of the intrusive rock at the top of Mt. Davidson. A film canister top is used for scale. The rock is composed of at least two different groups of minerals, dark and light. Most notable is that the dark minerals are in hydrous (water-bearing) minerals, biotite and hornblende. These minerals in abundance indicate that the magma origionally was rich in water. Having lots of water in the magma was important to development of the Comstock ore deposits.
Previous The Rock Next


Home Tour Physics Chemistry Earth Science lEnvironment Scams Lesson Plans