A cash book of Y Glog (Glogue) estate, Clydau, co. Pembroke, relating mainly to the slate-quarrying business of John Owen the younger (d. 1886), and recording payments from customers, mainly in co. Pembroke, and disbursements, 1867-1873 (ff. 1v-133), together with estate cash accounts and statement of rents, 1886-1891 (ff. 137-54).

Records relating to the Whitland and Gilfach quarries, comprising records of usage, [1890-1899]; slate prices, [1895]; account books, 1896-1918; report, 1897; agreements, 1898 and 1902; and lease 1898.

Correspondence relating to Tyrch Quarry, Mynachlogddu, machinery and stock, 1933-1942.

Records of the Precelly Green and Rustic Slate Company, previously known as the Gilfach Green Slate Quarry, including promotional items, 1897-1941; agreements for sale and purchase, 1919; memoranda, 1920-1934; production costs, 1920-1941; balance sheets, 1922-1931; and pay sheets, 1934-1939.