Why can't metamorphic minerals like garnet or kyanite form from a metamorphosed limestone?

Answer 1

"granite." I might also, I want to call attention to the idea of hydrothermal rocks as well. "Hydrothermal" means hot water, and hydrothermal rocks are formed by the action of hot water which contains dissolved atoms or ions. Hydrothermal processes are responsible for the deposition of metallic ores. These ore minerals are carried as atoms in solution and may crystallize in a particular sequence as the hot water moves away from a magma source or from the region of metamorphism.

http://honolulu.hawaii.edu/distance/gg101/Programs/program22%20MetamorphicRocks/program22.html it's a bit wordy but it will answer your qestion. it is all to do with the chemicals and creation that determins the type of metamorphic rocks. good site.

Answer 2

Well if you think about the chemical make-up of a limestone.... it's just calcium carbonate, really. So you have calcium atoms, carbon atoms, and oxygen atoms....

Whereas the chemical formula for garnets mean that they require elements such as magnesium, aluminium, and iron (and of course silicon). And Kyanite requires 2 aluminium atoms, one silicon and 5 oxygen.... so unless you've got metasomatism (hot metamorphic fluids moving through the rock and bringing in elements from elsewhere), then where the heck are you going to find all this Fe and Al in a limestone in order to grow those minerals?

Answer 3

Limestone has the wrong chemical composition, it's basically calcium carbonate.