Main Quarry or Castle Hill Quarry is a 14.7 hectares (36 acres) geological Site of Special Scientific Interest in Mountsorrel in Leicestershire.

[1][2] It is a Geological Conservation Review site.

[3] According to Natural England, this site "is probably the most dramatic and well-developed occurrence of asphaltite in Britain upon which international research into the origin of life on Earth has been carried out.

"[4] The site is private land with no public access.