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""The pyroxene-rich rocks which result from the contact metamorphism of impure limestones are described as pyroxene hornfelses (calc-silicate hornfelses).""

The above statement sounds inaccurate, since pyroxenes in hornfels are the byproduct of metabasite and metapelite metamorphism. If a ""limestone"" was that siliceous with a large mafic component, it would no longer be a limestone but a shale."