If Trump wants copper-nickel mining in Minnesota, he will need to stop tanking the economy, writes columnist Aaron Brown.

That means we can identify minerals using how they appear in doubly polarized light under a microscope! Hornblende (brown) with dark reaction rims in plain (singly) polarized light from a sample ...

It typically appears as a dark brown to black sticky substance and is rich in fulvic acid, humic acid, and various trace ...