A deep magenta color makes this piece gorgeous, and simply a strange color to see in English minerals. It turns out that inclusions of erythrite (i.e. cobalt) inside the calcite are responsible for the shocking hot pink color here. I have not seen many for sale, ever... I am told this was a small dripstone formation collected only sporadically, a long time ago. This piece was collected in 1974 by Greenbank family friend Anthony Walshaw, when exploring old workings in the Tynebottom mine. Illustrated in "Classic Minerals of Northern England," page 69, as a full-page photo. A close-up of this piece is also shown in a panel of photos on the front cover of the book.