Parting Shot

In their doomed attempt to keep me near the cutting edge of technology, one of my sons recently bought me a grey cylinder that, when connected to an electricity supply, answers (literally) to the name of Alexa. She speaks BBC English with a mellow, alto voice and can, sometimes, answer my questions. Early in our relationship, to see how smart she really is, I asked her a question with three answers, ‘How far is it to Glencoe?’

I must explain the extension to my title. I wrote a Parting Shot with the title ‘Nooks and Crannies’ for Elements, 8 (2), 2012, in an issue on ‘Minerals, Microbes and Remediation’, devoted to nooks and crannies on weathered alkali feldspar surfaces. For international readers, I explained that (according to the Concise Oxford English Dictionary) a ‘nook’ is ‘a corner or recess; a secluded place’ and a ‘cranny’ is ‘a chink, a crevice, a crack’. The reactivity of complex mineral surfaces is a complicating factor in ‘reactive transport’, particularly near Earth’s surface. The present issue provides me with an opportunity to dust-off a few old micrographs, images of considerable beauty in themselves, to remind readers that minerals are not just chemical compounds. It also allows me to introduce an intriguing discovery of the last five years. Some, but not all, feldspars are extremely effective at nucleating ice in clouds, and this may be related to nooks and crannies, not just to chemistry.

Can you locate Mercury
as it hovers over the Sun during its 2016 transit?