Goldfinger Posted April 2, 2007 Share Posted April 2, 2007 Don: If you scratch a piece of white porcelain with an unknown rock- sometimes it will leave a colored streak on it. This is a test they use to narrow down indentification of certain minerals. For instance hematite will streak reddish brown- pyrite will streak black- galena will streak grey.etc. Steve Quote Link to comment Share on other sites More sharing options...
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