Also known as Horse Crag Quarries, this site’s adit was initially driven in 1849 by John Barret to establish a connection with the extensive Tilberthwaite Copper mines. Its purpose was not only for drainage but also to facilitate the transportation of ore from higher levels. At the mouth of the adit, the Penny Rigg Copper Mill was constructed, serving as the copper-processing plant for this section of the mine. Stretching over 3,000 feet in length, the adit still serves as a drainage channel for much of the workings.

In 1933, John Willie Shaw observed that the adit had intersected an area of good-quality slate about 300 feet from the surface. He continued to work this area until 1938, at which point he became too old to continue. In 1989, George Tarr applied to operate Horse Crag as an underground closehead. He operated Horse Crag more or less continuously until its final closure in 2001.

• 1872-1876 Coniston Mining Co.
• 1912-1913 Central Chile Copper Co. Ltd
• 1914-1916 Langdale Silver-Lead & Copper Co.