Description: IDENTIFY AND LEARN: The full-color study guide contains information about each specimen in the set, allowing you to view each rock, gem, and crystal in more detail. Inspiring a love of science: We have selected samples to inspire a fascination with earth science and encourage exploration of the natural world. Rock Collection Mineral Gems Kit: This kit includes 15 different rocks, perfect for rock collectors, teachers or anyone who loves rocks. Great Science Gift for Kids: You can use it as birthday gift, Easter gift for kids. It has tons of rocks to identify, quality and keeps them entertained, it's fun and a great way to pass the time. High Quality: All rocks and minerals are ethically sourced and hand-sorted for the highest quality rocks and minerals. Specification: Material: Crystal Size Chart: Single Size: 20-30mm/0.79-1.18inch (there Is A Difference Of +-0.3mm/0.01inch For Irregular Size) Box Size: 12x20cm/4.72x7.87inch