Beautiful cut and polished Thunder egg

1 lb 3 oz aprox. One sticker says mercury strand. See pics. As found at a estate sale.

Info in general about thunderegg.

A thunderegg (or thunder egg) is a nodule-like rock, similar to a filled geode, that is formed within rhyolitic volcanic ash layers.[1] Thundereggs are rough spheres, most about the size of a baseball—though they can range from a little more than a centimeter (one half inch) to over a meter (three feet) across. They usually contain centres of chalcedony which may have been fractured followed by deposition of agate, jasper or opal,[1] either uniquely or in combination. Also frequently encountered are quartz and gypsum crystals, as well as various other mineral growths and inclusions. Thundereggs usually look like ordinary rocks on the outside, but slicing them in half and polishing them may reveal intricate patterns and colours. A characteristic feature of thundereggs is that (like other agates) the individual beds they come from can vary in appearance.