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Dwarves' Earth Treasures Online Museum:
Datolites of St. Louis Mine
St. Louis Mine, Calumet, Houghton Co., Michigan
Status: Now a private property (as of Aug 2019)

  The Red Metal Retreat book on the minerals and mine dumps mentioned that there are some agates at St. Louis Mine so we went there to investigate. Yep, there are some pink to purple agates all over but mostly really small and larger ones are usually fractured.  I stumbled into a datolite fragment when it was raining and that was an unexpected find. The rain brought its green color out that would have gone unnoticed when dry. So next year, I came back to the same place and poked at the rocks and one large datolite just rolled out. After that, I did some digging and found some more datolites. Turned out that they're grayish to green with so much copper specks all over and some are orangish due to iron straining (they're porous).  They may be not pretty datolites but they're quite cool. :)

You can click on the pictures to see larger pictures.
datolite datolite datolite

The 2nd Largest datolite
I have found so far

Glazed to bring out its green color.
Quite soft and porous

Gray-black color
due to tarnished copper

datolite

datolite

datolite

Orange color due to iron staining


datolite

datolite

datolite

My first whole datolite that rolled
 out when I poked at the rocks



datolite



Look for dark pine-green
 color in this one.