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Welcome to the forum AJK30. We love interesting rocks- especially with great photos. A few questions:How heavy is the rock? More or less dense than your average garden stone?Can you scratch the surface with a knife? Can you try a drop of acid to see if the rock fizzes?If you rub the rock on your most expensive porcelain bone-white china dining plate, does it leave an orange or red streak (just kidding about using your best china, but if you have an old piece of white porcelain- no glaze- give it a try). Any other information would be helpful... The orangish-brown is definitely iron oxide (like rust). There are some fine-grained, shiny, metallic looking spots in several of the photos- possibly specular hematite (iron crystals)? Looks like conchoidal fracture in several spots (like broken glass), which makes me suspect flint or chert. Appears to have faint stratigraphic layers in photos 2 and 5. Photo 4 looks like load casts- imagine pushing down on wad of silly putty sitting on top of bowl of jello. Possible chert nodule?
Thanks for the welcome and answers so far! Some of the info I'll have to get back to you on tomorrow because it's too late and I need to sleep . I did the knife test with a box cutter I had handy and it didn't seem to scratch the rock. In fact, it bent the blade a bit. It feels pretty heavy/dense. I guess probably a bit heavier than the "average stone", if there is such a thing. The outside is very smooth which I kind of assumed was an effect of the water, though it was on the shore. In pic one you can see some small holes and inside of them it looks like the rock is more coarse than on the outside.I will try to answer the other questions tomorrow. I think I have some porcelain to try that test, but the only acid I think I have handy would be vinegar. Is that strong enough?Thanks!