“ The object of these works is to recover a valuable deposit of Stream Tin which is found under the water in Restrongnet Creek, and lies on the rock beneath the mud and silt that form the bottom of the creek. “Stream Tin” is the name given to the tin ore found in diluvial beds, which is usually of very-superior quality to that worked from lodes; the best stream tin consists of pure crystals of cassiterite (Tin Oxide) called “black tin”, worn round by the action of the water. The Carnon Valley, which has its outfall in the Restrongnet Creek, was in the last century the site of one of the most important stream works in Cornwall; and the old streamers followed the tin bed someway down the creek, keeping out the tide by means of large embankments, of which a great part still remain, and removing the whole of the overlying silt to get to the Tin ore. The tide having broken in over the embankment about the year 1800, the works were abandoned; but about 1822 the working of the tin bed was resumed by mining under the silt of the creek, and this was successfully carried on for about five years. Sometime later a lower part of the creek was similarly worked, beyond the present working, and operations were continued until 1843; the remains of this working are still to be seen in the old mine island in the middle of the mouth of the creek.

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In 1871 the present operations were commenced for working the portion of the tin bed known to remain unwrought between the two old mines. Both of the old workings had been much troubled with water, the levels not always being deep enough to drain the dips in the rock; it was therefore decided in the present workings to drive a deep main level in the rock 4 ½ fathoms below the tin bed, to act as a drain for all the water and as a tramway level for removing the stuff. The workings were then commenced by sinking a shaft on the beach below high-water mark, the tide being kept out by a solid 9-inch square timbering built up from the rook around the shaft, with a wall of oak faggots around it, and 8feet of puddle between, made from the mud of the creek. The shaft was sunk through the rock to a total depth of 18 fathoms from the surface. An engine was required to pump out the water, which came mostly from the land slide and not from the creek; and the tramroad was laid 2 ½ feet above the bottom of the level, so as to form a reservoir beneath, in which the water could be allowed to accumulate to that depth without interfering with the road, in case of the engine ever stopping for a short period. An iron shaft was also sunk at the same time in the middle of the creek for securing good ventilation of the workings.

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The bed of tin gravel is sometimes 6 or 7 feet thick, and the men are then able to stand up to work; but more often they have to lie down when stripping, and sometimes where the bed is very thin they have to cut away some of the rock to enable them to reach in far enough. The mud when fresh broken is nearly black, and is dry and very tough; but after exposure to the air it becomes a light brown colour, and much softer and moist. Gas is given off by the mud and tin bed, which on two occasions has been found to take fire; and when the mud begins to fall it exhausts the air very fast, and on that account one party of men have the stripping of two or three levels in hand at the same time, changing from one to another as the air may change from better to worse. Sometimes, notwithstanding a good current of fresh air passing across the mouth of a stripping level and partly entering it, a candle will not keep alight near the falling mud, but gradually goes out, on account apparently of the absorption of oxygen from the air by the mud, and probably also the evolution of carbonic acid gas from the decomposition of organic matter. When exposed to the air the mud swells considerably, in consequence the writer believes of its containing a quantity of protosulphate of iron, which by absorbing oxygen from the air becomes converted into persulphate and iron oxide.

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The tin bed varies much in thickness and in productiveness; in some places it is as much as 7 feet thick and in others only 3 inches, and the produce ranges from 15% to only 0.1% of black tin (casserite). The top of the bed is generally nearly level, so that as the surface of the rock below rises or falls the gravel is thinner or thicker. The bottom of the bed is generally much the richest in tin, but there is sometimes a second floor of tin above, thicker than that below, and having a different quality of product associated with it, as if deposited in a different period. Some of the boulders found in the bed weigh as much as 3 cart (approx. 3000KG). In the old workings, and also recently in the new, some fossil remains of stag’s horns and bones etc. have been met with; and in washing the tin several small particles of gold have been found, some of nearly 4 grains weight, and some much larger nuggets of gold are stated to have been found in the old tin workings; gold is very generally found in small quantities with stream tin. “