Thunder egg 10-15mm oval flat beads (ETB01139) Pinolith agate often is found as

agate often is found as a round nodule

5 x 29 x 7

Red Horn Coral

but slicing them in half and polishing them may reveal intricate patterns and colors

as it depends on what the type of other mineral it is included in

Thunder egg 10-15mm oval flat beads (ETB01139) Pinolith agate often is found asThunderegg A thunderegg (or thunder egg) is a nodule like geological structure, similar to a geode, that is formed within a rhyolitic lava flow. Thundereggs are rough spheres, most about the size of a baseballthough they can range from less than an inch to over a meter across. They usually contain centres of chalcedony in the form of agate, jasper or opal,[1] either uniquely or in combination. Also frequently encountered are quartz and selenite