Hackmanite Hackmanite is a rare sulfur-rich variety of sodalite and a tenebrescent mineral, which means that it has the ability to change color when exposed to sunlight. This is a process that reverses when the light changes. This phenomenon is also referred to as reversible photochromism. Hackmanite gems are pale to deep violet when first mined, and fade to grayish or greenish-white once exposed to sunlight. However, hackmanite gems from Afghanistan and Myanmar do the opposite and usually change from colorless or creamy-white to pink-red or violet under sunlight.
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