From Dean Crawford
The valiant efforts of the Syracuse University Lava Project researchers to understand and control lava flows (3 August, p 40) might benefit from a look at what happens inside an industrial smelter. Integrated steelworks produce lots of slag, a waste product of smelting ore. As the researchers know, slags are not so different from lava in their physical properties, and are very well studied.
My years as a geologist working in ferrous metallurgy gave me many blissful moments studying the behaviour of slags. Whether a slag solidifies as a dense rock or porous pumice determines its suitability for use as an aggregate for road construction. As for the need to scale up experimental lava pits, industrial plants could supply researchers with an order of magnitude more material if slag were used.
Medowie, New South Wales, Australia
