Identify this rock with parallel lines

Question

Answer 1

Maybe chalcedony.

Hardness?

Comments

There are crystal faces on it which would rule out chalcedony. It looks most like quartz. Those lines don't look natural, but if they are, that would be quite unique.

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Those lines are absolutely natural..

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Looks like it is somewhat waterworn, which is perhaps the reason for the rounded nature and perhaps the etches. The closest guess I can think of is quartz, but you'd likely need to do a hardness test to know more certainly.