Answers


 * ~ Sample ||~ Identification ||~ Sample ||~ Identification ||
 * = 1 ||= gastrolith ||= 13 ||= coquina ||
 * = 2 ||= trilobite ||= 14 ||= conglomerate ||
 * = 3 ||= schist ||= 15 ||= geode ||
 * = 4 ||= limestone ||= 16 ||= marble ||
 * = 5 ||= pumice ||= 17 ||= petrified wood ||
 * = 6 ||= coal ||= 18 ||= fern fossils ||
 * = 7 ||= slate ||= 19 ||= lepidendron ||
 * = 8 ||= shale ||= 20 ||= coprolite ||
 * = 9 ||= brachiopod ||= 21 ||= worm burrow ||
 * = 10 ||= dinosaur footprint ||= 22 ||=  ||
 * = 11 ||= sandstone ||= 23 ||=  ||
 * = 12 ||= insect in amber ||= 24 ||=  ||