Figure 13.4
Gypsum crystals. These gypsum crystals in Mexico’s Cueva de los Cristales (“Cave of Crystals”) are some of the world’s largest crystals. (Note the people in the photo for scale.) This cave was inundated with groundwater until a mining company pumped the water out, revealing the large crystals within. Because these crystals formed through precipitation in water, they will not grow as long as the cave is kept dry.(© Carsten Peter/Speleoresearch & Films/National Geographic/Getty Images)