Bute & Mwyndy Haematite works

These two works were quite extensive across what we now call Cefn y Hendy and Mwyndy and drew employees here from many areas including Cornwall. This works was one of the drivers of growth of Miskin and Groesfaen in the late 19th Century.

The central core of the Bute site was just to the North of Bute farm with the Mwyndy works adjoining. This was operational in the mid to late 1800s and has now disappeared.

In the fields south of the road here there have been some small slag heaps found which have associated finds of pottery from the 3rd and 4th Century, which is of course, late Roman age

The following is an extract from an account of 1874 visit of Institute of Mechanical Engineers to Bute & Mwyndy Iron Ore mine published on Grace’s guide. This text is published under the creative commons Sharealike licence

“In returning from Landore to Cardiff, the Members visited the Mwyndy Iron Ore Mine, near Llantrissant, where they were received by the Manager, Mr William Vivian, who gave a description of the mine, and an account of the early opencast mining for iron ore and the manufacture of iron with charcoal, which were carried on in that locality several hundred years ago, until prohibited by an act of parliament forbidding the further use of the neighbouring woods for the requisite supplies of fuel; and a specimen of iron of excellent quality was shown, which had been produced at the time of those early workings, the name “Mwyn-dy” meaning “mineral house.”

About sixteen years ago a discovery of ore in the adjoining property led to the finding of ore in this mine also, and workings were commenced upon it. The deposit consists of brown haematite iron ore, occurring in a large bed or mass, between the carboniferous limestone on which it rests, and a bed of conglomerate. It lies immediately south of the edge of the South Wales coal basin, the thin shales overlapping the limestone close to the ore. The bed of ore was in some places from 35 to 40 ft. thick, and it dips north at an angle of about 45 degrees.

Like most other deposits of hematite iron ore in the same formation, it is found to be very irregular, large masses of ore being suddenly cut off by intervening bosses of limestone. This necessitates the employment of not less than one third of the miners upon “dead work,” exploring, and making communications for ventilation and for the conveyance of the ore; the total number of men employed is about 280.

The mine is worked both opencast and by mining underground, the extent of the workings being very considerable. The vertical depth to the present deepest point is 280 ft. from surface; and the water is pumped by two engines, each of which in winter raises upwards of 1,000 gall. per min., one of them being arranged to work on the dip. The ore is very variable in hardness, and a great deal of it requires blasting; from the levels it is brought out by horses to the vertical shafts and inclined planes, and on reaching the surface is tipped direct into the railway wagons, if sufficiently pure; but if not, it is first dressed by hand labour, being broken by hammers and then picked by hand to separate the iron pyrites and other impurities.

The total quantity of iron ore raised and sold has been over 620,000 tons, and the mine is at present in active work, yielding about 5,000 tons of ore per month. The quality of the ore is useful, yielding from 45 to 48 per cent. of metallic iron; it contains some silica. ”