Amethyst

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This compact amethyst cluster represents a fragment of what would have been an even more extensive vugh. It's likely to be sourced from the vast Agoenormous basalt fields in Brazil, measuring 16 cm × 13 cm × 4 cm in size. Amethyst is essentially a variation of α-quartz. The coloration comes from tiny amounts of ferryl iron (tetravalent). This state of iron is relatively unstable and reverts to ferric iron upon exposure to heat. As a result, heat treatment of amethyst produces citrine (yellow-orange in hue), which explains how similar specimens from the same field are artificially created by mimicking this process.