The thundereggs were first found as loose specimens along the river before the thunderegg-bearing stratum is discovered. The thundereggs usually contain narrow agate cores that it's tricky to get a bigger whole face while cutting them. The typical colors are deep red, brownish orange, and brown while yellow, pinks, whites, and lavenders had been noted rarely in vivid colors. The roughs will show hints of red agate.
    Their availability is limited due to the fact that it's expensive to import those thundereggs from Argentina due to their sizes as well as shipping and tariff costs.