Records of Cilgwyn Quarry Company, particularly accounts, 1879-1933:
- Particulars regarding state of quarry, rebuilding specifications, etc, 1880-1897
- Correspondence between quarry managers of Cilgwyn-Nantlle district dealing with wages, etc., 1895-1903
- Correspondence between directors and manager; notices to quit and details of houses owned by company, 1908
- Prices and particulars of slate prices in Cilgwyn and Nantlle area, 1887-1906
- Records of production and wages, 1882-1893
- Pay sheets, 1903-1933
- Miscellaneous items regarding time worked, rubbishers, bargainmen, suppliers of coal, c. 1905
- Time books (5), 1879-1905
- Wages books (2), March 1902-March 1905, November 1919-October 1929
- Average earnings book, August 1910-October 1929
- Rent accounts of company houses, 1865-1903
- Accounts relating to bargainmen, 1925-1927, rubbishers 1926-1928, country sales, 1909-1929
- Stock book, 1926-1928
- Order counterfoils, May-July 1907
- Consignment note counterfoils, August 1929-March 1931
- Paper entitled Value of Health Insurance; records regarding tonnage of slates transported and coal etc; monthly accounts, April 1915-November 1930; valuation account, 1922; rubbish account, 1921-1923, 1926
- Account of wages and other expenses incurred in transporting slate, October 1923-October 1929
- Accident record book, January 1897-May 1902
- General register of accidents, 1902-1927
- Reports of examination of steam boilers 1929
- Doctors receipt books, 1892-1904, 1895-1911, 1896-1910
- Compensation claims record, 1899-1929
- Compensation account book, 1928-1929
- Sketches and plans, 1891-early 20th century