Yellow Beryl

Heliodor is the yellow to greenish-yellow variety of beryl, coloured by iron, its name from Greek helios, sun, and doron, gift, the gift of the sun. It shares the beryl family properties of hardness 7.5 to 8 and hexagonal prismatic crystals, and it grades into golden beryl on one side and into green aquamarine on the other, the boundaries being matters of trade convention rather than sharp mineralogical lines. Fine heliodor came notably from Namibia and from Ukrainian and Brazilian deposits. Because it was distinguished and named only in the early twentieth century, heliodor carries no ancient tradition, and older references to yellow gems are as likely to mean topaz, citrine or chrysoberyl. Its modern metaphysical associations, generally solar, warmth, vitality, the solar plexus, follow directly from the golden colour and the name and belong to recent crystal practice.

The beryl family, of which heliodor is a member, left an unexpected mark on everyday language: German Brille, spectacles, descends from Latin beryllus by way of Middle High German berille, because the earliest eyeglass lenses, ground in the thirteenth century, were made from clear beryl before glass-grinding improved enough to replace it. Gem-grade yellow beryl is mined today chiefly in Brazil, Namibia, where it comes from the same pegmatites as blue aquamarine, and Madagascar, and because the variety was named and separated from plain golden beryl only in 1910, references to a yellow beryl gem before that date cannot be assumed to mean this specific stone rather than citrine or topaz.

Heliodor is the yellow to greenish-yellow variety of beryl, and the most useful thing to say about it is how many familiar gems are the same mineral.

Beryl is beryllium aluminium silicate. Pure, it is colourless. Trace chromium or vanadium makes it green and it is called emerald. Iron in one oxidation state makes it blue and it is aquamarine; iron in another makes it yellow and it is heliodor. Manganese makes it pink and it is morganite. With no colouring element at all it is goshenite. Five gem names, five prices, one species, and the difference between them is a fraction of a percent of impurity.

Heliodor takes its name from Greek roots meaning gift of the sun, and the name was coined in the early twentieth century for material from what was then German South West Africa, now Namibia. It is therefore a modern trade name attached to a stone that had no separate identity before, which is worth saying plainly, because the name's Greek form invites the assumption of antiquity.

Beryl crystallises in the hexagonal system and forms long prisms, sometimes very large ones, in granitic pegmatites. Crystals of several metres are recorded. The mineral is also the principal ore of beryllium.

Where a classical or medieval source names beryllus, it is generally not referring to this stone or to any single one. As with topaz and sapphire, the ancient term describes an appearance, and matching it to a modern species is a judgement rather than a translation.