Canadian Rockhound: Hackmanite

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Hackmanite
By Sandra Downs

What mineral changes color from white to pink and back again? Hackmanite! It's an unusual tenebrescent mineral found in several localities around the world, most notably Bancroft, Ontario and Mont. Saint-Hilare, Quebec.

While many sodalites from this region are white, only hackmanite shows photochromism. When freshly dug from the ground, it's pink. It quickly fades to white under white light or sunlight. But put the specimen in a darkened closet and within a few days, it gradually turns to pink. To accelerate the process, place the specimen under a shortwave ultraviolet lamp in a dark room. Instant pink! The deepness of the pink color varies from place to place, and some specimens show a violet glow. A persistent raspberry-red can be coaxed out of the showier pieces.

In Bancroft, hackmanite specimens are found at the Davis and Morrison Quarries, deep in the woods along the York River. In Mont. Saint-Hilare, field trips to the Poudrette Quarry uncover occasional pieces of hackmanite. If you're a fluorescent mineral collector, this Canadian classic is a must!

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