Interestingly, Dunn and Bundy measured the resistivity of Ca under pressure finding it to increase above 0.4 ohm at 4.2 K and 30 GPa, before dropping to 0.2 ohm at 44 GPa at the same temperature, and vanishing below 2 K, possibly due to a superconducting state transition . Therefore, the inverted integrated-charge trend (Figure ) might also be correlated with the electrical conductivity of Casc.