Comprises material relating to Mona Mine Company:
- Correspondence between the Earl of Uxbridge and Thomas Williams, 1787-1800
- Letters from S. Taylor to John Price and William Cary, mainly about the Stanley enterprise near Liverpool, 1798-1800
- Photocopies of copper accounts, Parys Mine, 1782-1793 and Mona Mine, 1786-1793
- Accounts, 1782-1800
- Ledgers, Mona Mine Company and Mona Smelting Works, etc., 1818-1865
- List of arrears due to the Mona Mine Company with a rental of their estate, 1802-1812