Wavellite sorbet

What better for a hot summer’s day than a lovely ball of cooling bluey-green mineral ice cream, whose flavour I shall leave at your discretion. The specimen in the photo displays both common habits of this hydrated aluminium phosphate, spheres and radial sprays (bottom) of needle shaped crystals. Irregular masses can also form, and, very rarely, prismatic crystals.

The usual hue is green, though it can also be yellow, brown or white. It’s named after its discoverer, who found it in an English quarry in 1895. Its geological setting is low grade metamorphism of aluminium rich rocks, at low temperatures and pressures and phosphate rocks that have been altered by mineralising fluids. Wavellite is secondary, formed by the hydration of primary minerals during and after metamorphism. It has sometimes been cut into dome shaped cabochons for collectors, and is used as an ornamental rock. It is found in Arkansas, Bolivian Germany and the original quarry in Devon. 


Image credit: Jake Slagle

The Louisville Mega Cavern

What do you do with an abandoned mine?

Some entrepreneurs in Louisville, Kentucky had an innovative idea—turn it into an underground theme park.

Earlier this week, the Louisville Mega Cavern opened its newest attraction—a subterranean network of 45 bike trails complete with jumps and all the cycling hoopla you could imagine. And that’s not all—the site also offers a zip line, a tram ride, a ropes course, a Christmas lights show… all of it underground.

The Louisville Mega Cavern used to be a limestone quarry operated by Louisville Crushed Stone. Originally opened in the 1930’s, this mine supplied a large amount of stone used for road construction in mid-century America. The 100-acre man-made cavern has become famous for its other uses though—it was designated as a bomb shelter in the 1960’s and then sold in 1989 with the intention of becoming a high-security office area (there are still some businesses in it, in fact). In 2009, investors came up with another idea that was a bit more tourist-friendly…. creating an underworld of fun. Thrill-seeking, rock-loving fun.

As a geologist, I have to wonder about the long-term stability of a man-made cave full of bike trails and roads. But would I pass up the opportunity to zip line through some exposed limestone? No, no I would not. Sounds like an awesome new way to do fieldwork.


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Photo Credit: Jacob Parker/ WFPL