Dictionary of Geotourism

2020 Edition
| Editors: Anze Chen, Young Ng, Erkuang Zhang, Mingzhong Tian


Reference work entry
DOI: https://doi.org/10.1007/978-981-13-2538-0_2318

The composition of spinel is MgAl2O4, and it is an oxidized mineral. It often contains iron, chromium, manganese and zinc. The crystals are isometric and often appear as octahedrons or aggregates of octahedrons and rhombic dodecahedrons. It sometimes appears as platy, granular and dense aggregates. It can be red, green, brown or black with white streaks. It has transparent to opaque diaphaneity, a vitreous lustre, a specific gravity of 3.5–4.1, a Mohs scale hardness of 8 and conchoidal to uneven fractures. Spinel mainly forms in several types of metamorphic rocks, such as serpentine, gneiss and marble. It can also form in mafic rocks. Transparent spinel with bright colours can be used as gemstones. Gem-grade spinel is mainly magnesium aluminium spinel, which has various colours ranging from colourless, pink, red, purple, light purple, violet, blue, and yellow to brown. Spinel is mainly categorized according to its colour, such as red spinel, orange spinel, violet spinel, and blue...

This is a preview of subscription content, log in to check access.

Copyright information

© Springer Nature Singapore Pte Ltd. 2020