Beryl heliodor

Heliodor is the golden yellow gem variety of beryl due to the isomorphous substitution of aluminum by ferric cations. It is also known as yellow beryl if the golden tint lacking. Good colored material is relatively rare. As other gem varieties of beryl it is found in granitic pegmatites in Brazil in the Ural Mountains (Russia), and Namibia. 

An example of a cyclosiHcate is beryl BejAljSi Ojg (Figure M58). It usually occurs in green, bluish-green, yellow or pink hexagonal prisms. Transparent and colored gem varieties include emerald, aquamarine, heliodor and golden beryl. In the tourmaline... 

Varieties of minerals are a subdivision of species and their names are not recommended by the IMA and are not constrained by this international body. Varieties are principally used by gemmologists and commercial enterprises. In many cases, the criteria for distinction include color (e.g., ruby and sapphire are varieties of the species corundum emerald, aquamarine, heliodor and morganite are varieties of the species beryl). No mineral species has as many different variety names as does a-quartz (agate, amethyst, chalcedony, chrysoprase, citrine, cornelian, and many more). 

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