🔎 UNIDENTIFIED Rock found on Marthas Vineyard

[Samoset99]

Found this striped/layered rock on MV. Any ideas what it it? Thanks!

 

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[robcip]

Im guessing its a Gneiss rock

 

[ToddsPoint]

Quartzite. That rock started out as sandstone. A sedimentary rock. That’s why it is banded, showing the different layers that were put down. Then it was plunged deep into the earth, like 6 miles minimum. The heat and pressure changed it into quartzite, a metamorphic rock. Quartzite polishes up nicely. This is a similar piece of quartzite that has been drilled and polished.

 

[Samoset99]

Quartzite. That rock started out as sandstone. A sedimentary rock. That’s why it is banded, showing the different layers that were put down. Then it was plunged deep into the earth, like 6 miles minimum. The heat and pressure changed it into quartzite, a metamorphic rock. Quartzite polishes up nicely. This is a similar piece of quartzite that has been drilled and polished.View attachment 2102424

Thanks for the replies. Here's another from the beaches of MV, a baseball size rock made of small chips of rocks, a conglomerate I assume. Haven't found another like it. Makes a cool paperweight.

 

[ToddsPoint]

If the matrix holding those grains and pebbles together is good enough that one might polish up real nice. When the pebbles are rounded it’s a conglomerate. If the pebbles are sharp and angular it’s a breccia.