Crystals need room to grow Few grow perfectly in nature. With adequate space crystals grow in igneous, metamorphic, and sedimentary rock. Most crystals, growing at the same rate, become irregular as they touch neighboring crystals. However, Diamond, which grows early, may show a characteristic flat face and well-formed crystal even though it formed in solid rock. |
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Visitors may touch all rocks and minerals featured on this page. |
Not all minerals are crystals Made of silica and water, opal has nearly the same chemical composition as quartz yet occurs as a formless mass from a solution of silica in water. Opal remains light and porous and never forms distinct crystals. |
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Few collectible crystals grow from vapor Some elements and compounds dissolve in heated gasses including water vapor. Vaporized minerals condense when they meet cooler surroundings. Sulfur crystals may form around volcanic vents (fumaroles) where gasses and heated ground water emerge. |
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