Fran, calcium is usually classified as an alkali earth metal but it is intriguing in this context for two other reasons.
Calcium is indeed a part of some HTSC compounds which came out of the early IBM replications. The group called BSCCO (pronounced "bisko") has calcium as a component, but notably the element itself is superconductive on its own which would seem to exclude it from the new discovery. Also as it turns out - calcium is an elemental HTSC only under intense pressure. The crystal structure changes to become superconductive at -244oC at ultrahigh pressures of above 200 GPa. Thus it seems to fail on two parameters for the new discovery from India (assuming it is replicated). The legends you refer to about levitating stones are interesting and could point to some kind of residual pressure effect in calcium, but is there real science involved, or just myth? From: Roarty, Francis X Calcium is a transition metal… found in limestone and coral and several levitation legends. From: JonesBeene https://arxiv.org/abs/1807.08572 “Evidence for Superconductivity at Ambient Temperature and Pressure in Nanostructures” Dev Kumar Thapa, Anshu Pandey (Submitted on 23 Jul 2018) India Institute of Science. Specifically the authors who appear to be relatively unknown, found the HTSC and Meissner effect in silver nanoparticles embedded in a gold matrix. However, it seems clear that they expect more depth to the discovery than only gold and silver - and hopefully other less expensive combinations may turn up. They started with a view towards discovering “non-phonon based electron pairing mechanisms” – IOW plasmonic. Au and Ag are of course expensive precious metals with excellent normal conductivity, both thermal and electric, and notably both have low electron-phonon coupling and are not known to exhibit a superconducting state independently. Is that basic set of parameters the start of a formula which leads to other pairs such as zinc and cadmium or nickel and palladium? If there is broader applicability to other related pairs of transition metals, and of course if this finding is easily and quickly replicated – then it likely could be the start of an international race… which is reminiscent of the discovery of HTSC in copper oxides in 1986 by IBM researchers Bednorz and Muller, who were awarded the 1987 Nobel… and which scenario could happen again here if this is real. Of course, the IBM discovery failed to live up to the early hype. Jones
