Surface Work

Ore Dressing
Treatment of the mined copper ore for selling to the smelter was known as ore dressing, and in common with other copper mines in Cornwall this work was mainly carried out by women, sometimes known as  Bal Maidens.

It was not a full time job and in some months there were no entries for ore dressing expenses.  The usual rate of pay was 9d (£0.037) per day from 2 to 25 days per month, and if a man was employed for a few days his rate would be twice that of the women. In total there were forty-five different women who worked on the Wheal Agar dressing floors but the maximum in any one month was nine. The closest dressing floors to Windstraw shaft would have been at Tolskithy and perhaps there was another location nearer Western Engine Shaft.

The dressing of copper ores in the 1850's included the following operations:-

The dressing of tin ore was different from that of copper in that the rock containing the tin ore had first to be crushed to release the cassiterite, which was then concentrated by gravity separation methods to make it suitable for smelting in Cornwall. Crushers known as Stamps would have been used and these were powered first by waterwheels and later by steam power.  In the cost book there is reference to repairs and rent of stamps at Tolskithy, and these were probably powered by waterwheel. The chimney stack at Tolskithy which can be seen on the south side of the A30 road viaduct marks the position of an engine house which powered a battery of stamps there, but this came after the date of our Cost Book.

Weighing, Mixing & Dividing
Weighing of ores was carried out usually once per month by a pare of men for 6d (pence) per ton.

Mixing and dividing did not necessarily occur in the same months as the weighing. I do not know the purpose of this process unless it was the mixing together of parcels of ore from different tributers, and I should be pleased to have any information. The men who carried out the mixing and dividing were paid at the same rate as for weighing, but the quantities were greater. The total weight of ore recorded in the Cost Book which was mixed and divided was 738 tons, compared with 309 tons weighed.

Sampling & Bruising Samples
Usually once every two months sampling of the ore for assaying was conducted by one of the captains who charged fees of 13/- or 15/6 (£0.77).  In the same months as the sampling there was an entry for 'bruising samples', which I understand is the preparation and dividing of samples for assaying.  The only person doing this work was a lady called Mary Thomas and she was paid from 2/- to 3/- per month.  Her total pay for 50 months came to £2.63.

Assaying
The charges for assaying were recorded in the same months as the sampling and the number of samples varied from 8 to 20.  In total there were 273 copper assays at 2/- each and 27 tin assays at 1/- each. The names of 15 different assayers were listed.

Cleaning Stamps Leat
With the small amount of tin being produced the stamps were probably operating at intermittent periods. There is evidence to suggest that pumped mine water was conveyed by a leat to the stamps, and maintenance work on the leat was carried out on a number of occasions by the mine carpenter and others.

Repairing Burning House
The burning house was another name for a calciner where the tin ore was put into a furnace to remove unwanted minerals particularly arsenic.  The burning house draft required maintenance at times and these are listed in the Cost Book.  The remains of a calciner labyrinth for the collection of arsenic can be seen close to the A30 viaduct in the Tolskithy valley but it was probably of a later date. (See below)

View from Tolskithy dressing floor area facing north across the A30. One of the 3 stacks was the flu exit from the labyrinth above, which is hidden in the valley under the pole on the left.

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