Science X Maxi Crystals & Gemstones: Almost all solids found in nature consist of crystals. Crystals are so small that they cannot be seen with the naked eye. Minerals, which are the building blocks of crystals, liquefy inside the earth under strong pressure & high heat. When minerals cool back down, they solidify in an impressive, uniform system, into crystals. The process often takes a very long time. The especially rare & beautiful crystals & minerals, which particularly fascinate us due to their shape & colour, are called gemstones. Want to learn more about these natural wonders? Come along on a journey through the galaxy of crystals & gemstones.