Dwarves' Earth Treasures Online Museum:
Caledonia Datolites found by JA
Caledonia Mine, Mass City, Ontonagon Co. Michigan
Field-collecting Status: Private Property! Open only to Arranged Collecting Tours

    I joined few of 1990s' collecting tours that entered the adit of Caledonia Mine to collect the datolites in one of those sloped mining rooms. There were a lot of small datolites all over after having came out of the mud-filled cracks and large nodules are sparse as expected. Since the mining rooms are sloped, it wasn't easy to trek around on the slippery rocks. There were some bats flying about, but I don't see how can anyone be afraid of those harmless flying creatures. :) Most of the datolites from the seams in that room are brown to reddish brown, sometimes with bleached rims. I have found some orange and clear datolites with episode inclusions in a room, but I think that this room is no longer accessible. I also picked up some orangish datolites from the road and outside mine piles. The last time I went there were in 1990s so I miss going in there.

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datolite
One of several largest & best datolites found by JA so far (1990s)
datolite datolite
Typical color of Caledonia Mine.
Has copper specks all over.
1990s
 Light orange nodules, rare find.
May be from a different seam.
1990s
datolite datolite
Another typical datolite from Caledonia Mine
1990s
 Rimmed with reddish copper inclusions
1990s
datolite datolite
Found in the road to the mine
1990s
 With epidote inclusions (different seam)
1990s
datolite datolite
With epidote inclusions (different seam)
1990s
 Common brown datolite
1990s