How the red in Red Mountain came to be Dear Science Mine: Why is Red Mountain belong primarily to the Mountain red? Greyson Formation, a dark-colored — A Butte resident mudstone that has largely been altered to slate. During the long time — Karen Porter is a senior Answer: Red Mountain is one of that the original sediments were research geologist for the the three peaks that form the skyline subjected to deep burial, lithified to Montana Bureau of Mines and of the Highland form rock, and finally uplifted to Geology, Butte, Montana, and Science Mountains form mountains, the rocks underwent may be reached via e-mail at Mine south of Butte. numerous chemical changes that
[email protected]. These moun- formed new minerals in the rocks. tains are up- In the Greyson Formation, a — How does a GPS work? lifted blocks of large amount of iron sulfide accumu- Why is the sky blue? Need to very ancient lated to form such minerals as pyrite. know? You ask the questions and sedimentary When the iron sulfide minerals Montana Mind Expansion — a rocks (around 1 weather, the iron “rusts,” or oxi- group of Butte professionals and billion years dizes, turning the rock various lay people with expertise in all old) that were shades of red. fields of science and engineering once deposited Thus, Red Mountain is red — will provide the answer. Send as sand and because of the weathering of the KAREN PORTER your most perplexing query to mud in a large iron-sulfide minerals within its The Science Mind, care of The depression that occupied most of rocks.