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Ordinary rock??


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Hi guys and gals,

     I found this today and what grabbed my attention was the exterior had the appearance of contractions but I'm really not sure what to think. It attracts a magnet, feels dense for its size. It's 65gr, approximately 2"x1-9/16"x1". I opened a window and polished to 600 and there are no chondrules, but I do see those lines within the matrix. I guess what I mostly would like to know is that in the likelihood that this is terrestrial, what are the tell tail signs seen under magnification like a magnify glass strength or loop that can help one positively identify shock veins apart from just ordinary cracks filled with minerals washed in. 

IMAG0169.jpg

IMAG0170.jpg

IMAG0167.jpg

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If it were a chondrite you would see metal flecks in the polished window.  It appears to be terrestrial to me.

Contraction cracks occur in the fusion crust as it cools rapidly, they don't "crack" all the way into the stone beneath, such as you see here.

Shock veins are veins of shock melt, it appears that physical cracks are visible in your window.

Good pictures, keep looking.

Edited by Mikestang
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Thanks Mike, I'm glad you clarified the contractions part because I was under the impression surface tension from the rapid cooling could cause ~some~ fracturing beneath the surface as well apart from just the fusion crust contracting, not thoroughly of course.

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