FAMOUS MINERAL LOCALITIES:
PENBERTHY CROFT MINE, ST. HILARY, CORNWALL, ENGLAND

John Betterton
with contributions by David I.Green & John Mason

Penberthy Croft Mine was noted as a locality for pyromorphite and mimetite in the mid-nineteenth century. Since that time an increasing number of minerals have been reported from the mine, making it one of the most diverse and important mineral localities in Cornwall. An extensive range of supergene minerals occur on the old mine dumps and fine specimens of bayldonite, pyromorphite, mimetite, linarite, plumbogummite, carminite, and philipsburgite were collected from the underground workings in the early 1990s. To date, the locality has produced 90 confirmed mineral species including the first, or joint first, recorded British occurrences of jeanbandyite, natanite and segnitite. The type specimen of the copper lead arsenate mineral bayldonite is from Penberthy Croft. Most of the supergene minerals are found in cavities associated with strongly oxidised gossan in vein quartz, or in the blue and green stained mineralised slate.

Chalcotrichite in quartz veinstone, the upper patch is 4 mm across and is partially replaced with chrysocolla. Richard Bell collection. Photo: David Green.

Radiating sprays of bright green mixite up to 1.2 mm in diameter. John Betterton collection. Photo: David Green.