0
$\begingroup$

Found today in a creek in Indiana, has a geode look and the broken edge shows red opaque facades.

enter image description here

$\endgroup$
  • $\begingroup$ you need to give a lot more information about it,please take a look here earthscience.meta.stackexchange.com/questions/124/… and edit this new information into your question to make it possible to answer this. $\endgroup$ – trond hansen Apr 23 '19 at 5:43
  • $\begingroup$ looks like jasper, a form of quartz $\endgroup$ – haresfur Apr 23 '19 at 7:10
3
$\begingroup$

Your rock appears to be quartz var. chalcedony (jasper) with the interior being quartz pseudomorph after another mineral probably calcite or aragonite. I've seen a number of quartz pseudomorph after calcite from Indiana over the years but I do not have a good reference for Indiana pseudomorphs.

$\endgroup$
0
$\begingroup$

Gary's answer is valid but I might suggest that Cinnabar is also a possibility. To give a definitive opinion we really need to know how hard the material is.

$\endgroup$

Not the answer you're looking for? Browse other questions tagged or ask your own question.