Need help identifying this rock, Found in northern MN

Looks like a porphyritic basalt.

http://www.geo.mtu.edu/KeweenawGeoheritage/BlackLavas/Basalt_Textures.html

Large phenocrysts are plagioclase feldspar, groundmass is typically very fine grained olivine and pyroxenes.

BC

 

yes, that was my diagnosis as well

 

So @ReevesN76R

are you happy with the answer ?

 

The porphyritic basalt seems to be correct. I have been collecting rocks and minerals for 55 years.

 

Cool rock.

 

a rhombic porphyry most likely - how come you found it in Minesota, tough? They are more common in the scandinavian region around Oslo, Norway.

 

The rock is rounded and river worn, so it was not taken directly from an outcrop. It has probably been carried by a glacier or an ice sheet during the last glacial period. It may have traveled a long way south from some volcanics in Canada.
I have found identifiable rocks in unexpected places, but only where glaciation was available to transport them.

 

The Great Lakes region is rich is rocks and ancient volcanism.
Just over a billion years ago the continent was on the verge of breaking up,
https://en.wikipedia.org/wiki/Midcontinent_Rift_System
http://academic.emporia.edu/aberjame/student/woodbury2/rift2.html
https://en.wikipedia.org/wiki/Geology_of_Minnesota

 

It looks like what I have known as a "pudding stone"

 

Pudding stone is a sedimentary "conglomerate" of rounded pebbles in a fine matrix. It looks like a cut slice through a plum pudding.

The rock pictured was volcanic, having a fine green basalt matrix with large phenocrysts of feldspar. A rock with phenocrysts is described as a porphyry, or as being porphyritic. The phenocrysts are crystallised out of the melt over many years as the magma gradually rises up towards a volcanic vent. The fine grained matrix indicates that it cooled quickly once it reached the surface which is why it is known to be a volcanic rock.
https://en.wikipedia.org/wiki/Phenocrysts