Rare minerals from pegmatites
As molten granite crystallizes, the melt that remains becomes enriched in water and rare elements such as boron, lithium, tantalum, and niobium. These elements concentrate in the melt because they are not taken up by the minerals crystallizing from it. Eventually, enough water builds up that steam forms. Gem and ore minerals containing rare elements form in the pockets of steam- and water-rich melt. In the presence of water, minerals can grow to enormous sizes, forming rocks known as pegmatites.
Topic: Earth Science
Subtopic: Minerals and Resources
Keywords: Chemical elements, Hydrogeology, Magmas, Natural resources, Pegmatites
The large groups of pink crystals of the boron-bearing mineral tourmaline and the tiny purple crystals of the lithium-bearing mineral lepidolite grew from a melt consisting of lithium, boron, and water-rich silicate.