EOSC 118 Lecture Notes - Lecture 15: Beryl, Miarolitic Cavity, Pegmatite
Document Summary
Classifying gem beryl based on economics = 2 categories: related to pegmatite + not related to pegmatite. Yields largest amount of gem beryl since pegmatites = easy to find and can host many other gemstones. However, may not be as valuable - most valuable found in unusual environments (eg. emeralds from columbia, blue beryl from yukon, red beryl from utah) Since gem beryl has beryllium in structure, search for beryllium = good way to find gem beryl. 4 geological models of beryllium enrichment = pegmatitic, magmatic, metamorphic + secondary can lead to crystallization of gem beryl. Environment also needs to support production of relatively large (open space cavities in rocks) + transparent/semi-transparent stones (stable growth environment) Beryl = common in granitic pegmatites and gem beryl = typically found in pegmatites w/ rare elements, eg. lithium, cesium Can also exchange elements with rocks they come in contact with, such as cr and v.