Large Rough Gemstone Mining Kit. Yellow Bag (large gemstone) contains over a half-pound of gems, crystal, pyrite, and arrowhead. The bag comes with an identification guide to identify the gemstones and where they can be found around the world. All you need is a sifter or colander and some water. This is a great hands-on learning activity for kids. These rocks and gemstones are from all over the world and we guarantee large specimens, not small pickers.