1000 Crystal are best gathered with a metal pick or with certain creatures; stone picks can work but provide a very low drop chance. It can be acquired by mining white crystals. White crystals are the primary source which can be mined, stalactites in caves also provide crystal. Some others are just decorative. An even better way to gather crystal is the lunar biome on genesis by harvesting the crystal bushes with a Bronto, this can be boosted even more with a mate on a Deinonychus, because a Deinonychus can jump equally how much weight the rider has. You can also use a Magmasaur, Anky, Tek Stryder, and many other dinosaurs to harvest white crystals as well. The Stryder, while not having the greatest collection rate, is the best resource collector in general due to being able to connect to dedicated storage boxes in your base and send resources back to them from anywhere on the map.