Introduction to TUCSON 2024: Celebrating Pegmatites

• Published in: Rocks & minerals Vol. 99; no. 1; pp. 8 - 9
• Main Author: Cook, Robert B.
• Format: Journal Article
• Language: English
• Published: Washington Taylor & Francis 02.01.2024; Taylor & Francis Inc
• Subjects: Apatite; Beryl; Beryllium aluminum silicates; Cassiterite; Cesium; Crystals; Current sources; Economic importance; Gems; Grain size; Igneous rocks; Lithium; Magma; Mica; Mineral exploration; Mineralogy; Minerals; Monazite; Muscovite; Niobium; Pegmatite; Phosphates; Rock intrusions; Spodumene; Tantalum; Tin; Topaz; Uranium
• ISSN: 0035-7529; 1940-1191
• DOI: 10.1080/00357529.2023.2253092

Pegmatites are igneous dikes or sills, often of felsic or granitic composition and characterized by crystals of unusually coarse grain size. They are economically important and have been mined for muscovite, feldspar, quartz, lithium minerals, tantalum and niobium minerals, tin, cesium, gemstones, and mineral specimens. Placers derived from them are current sources of tin and tantalum concentrates. Pegmatites of interest to the collector or jeweler are primarily those found intimately associated with cooling granite magma that, with luck, are also cavity-bearing. Many are compositionally zoned, and a few are noted for exceptionally large crystals, particularly those that produce spodumene. They are often divided into families based on minor element chemistry. The wide array of gem pegmatite species can include beryl and the beryl family gems; spodumene; topaz; the garnet group, especially spessartine and almandine; amblygonite; brazilianite; euclase; chrysoberyl; petalite; pollucite; tantalite; cassiterite; apatite, monazite, and a wide variety of other minerals including phosphates; and a suite of diverse uranium minerals.