Unknown rock

[Turtle71]

Pleas help me identify this rock it was found on the shores of lake huron around tawas michigan

 

[Red-Coat]

It appears to be red quartz/quartzite porphyry. There are masses of it in the Huronian Ridges north of the lake, and it's widely distributed southwards as rounded glacially-transported erratics from pebble-size up to massive boulders.

 

[fuss]

I have found some of these myself but in WI out of lake MI. They aren't quartzite or quartz (though there is some quartz) but some kind of metamorphic rock, its hard to tell. The red is k-feldspar, the black minerals are hornblende I think, and not sure of the greenish stuff, i don't think epidote though. The "honeycomb" patterns are interesting and I have seen it on several of these.

 

[Red-Coat]

I have found some of these myself but in WI out of lake MI. They aren't quartzite or quartz (though there is some quartz) but some kind of metamorphic rock, its hard to tell. The red is k-feldspar, the black minerals are hornblende I think, and not sure of the greenish stuff, i don't think epidote though. The "honeycomb" patterns are interesting and I have seen it on several of these.

Even allowing for the fact that one is wet and the other is dry, I don't really see much petrological resemblance between what you found and the OP's rock beyond the colouration.



The Huronian Ridge is a mixture of igneous rocks and beds/intrusions of red porphyritic quartz/quartzite with various degrees of metamorphism. Quartzite is metamorphosed quartz.

 

[fuss]

Interesting, I completely see it. The reddish potassium feldspar may have a more advanced degree of weathering on mine (not sure if lake MI is a better rock tumbler than Huron), but the green and black minerals look strikingly similar, same honeycomb pattern..I think if turtle is willing to crack the rock in half and post some images we can learn a lot more about its composition, as for mine...I like my paperweight, so I will have to take a trip to lake to grab another one to crack.