The information which appears in the following tables is the same as that published in the annual editions of the Mineral Statistics, now re-arranged in a mine-by-mine format. Some editorial judgement has been exercised in re-compiling the material, in order to link returns together and provide for necessary cross-referencing, but wherever possible the mine names, production record, ownership, management, employment and even comments are given just as they appeared in the original. If any category of information is missing under a mine name, or if the series cover only a few years, or indeed if an entire entry is not included, it is because there were no returns in the Mineral Statistics. To facilitate the alphabetical arrangement of the material, we have omitted the common prefix "Wheal" from mine names.

A problem that has occured in earlier volumes in this series and which has also been apparent here, is that of the random transfer of returns for some mines between neighbouring counties. The original Mineral Statistics may have incorrectly located some of the returns for 21 Cornish mines in Devon and 11 Devon mines in Cornwall. There is also the possibility that some Cornish material was also wrongly distributed under some other English and Welsh counties. The totals for all of the counties concerned were accordingly distorted by these errors. In the past we have sometimes attempted to correct these problems by transferring the relevant material between the counties. Here, however, we have left them unchanged in the interests of the faithful reproduction of the original and acknowledging the possibility of our own error. The probable misplaced entries are indicated in the Mine Tables and are as follows:

Not all entries for all of these mines were wrongly located. Some of their returns were under the correct county. One particular problem arose for South Bedford and East Gunnislake which were worked for a long time as one mine, straddling the river Tamar border between Devon and Cornwall. The ownership returns appeared in one listing but production was given in different years under both counties. It is hoped that on completion of this series it will be possible to publish a full calendar of mislocated returns and to adjust the county totals tables accordingly.

The only new material that has been added to the Mine Tables is some additional cross-referencing information, the adjustment of some locations for current usage, and Ordnance Survey Grid Reference numbers. The Grid References have been derived from our own research, checked against those provided by A.K.Hamilton Jenkin in his seminal series The Mines and Miners of West Cornwall. In editing the material, close attention has been paid to J.H.Collins, Observations on the West of England Mining Region and H.G.Dines, The Metalliferous Mining Region of South West England, as well as other established reference works on Cornish mining. A number of the mines making returns were not referred to in any of these texts, however, and their precise location frequently remains unknown. We would like to thank Alasdair Neill and Justin Brooke for their invaluable advice in resolving many particularly difficult locational problems.

Four principal categories of information are included for every mine, where they are available. Production data are given by type of mineral produced and often include ore output, metal content, and value -- the latter sometimes being calculated by assay and average market price. The absence of detailed production returns under a particular mine name should not necessarily be taken to imply that the mine was not working in those years, since its output might be disguised in the county aggregate figures, sundries or joint returns listed under other mines. Wherever possible we have tried to indicate such listings through cross references in the Comment section. For copper mines, the comment section has also sometimes been used to indicate the method of sale of the ore; the sales at the Cornish ticketings being indicated by (C), those at the Swansea ticketings by (S) and private contract agreements by (P). For iron mines, the comment is used to indicate the types of ore being produced; this was commonly red/brown haematite (RH), spathose (SP) and magnetite (M0). The returns for the production of the different minerals on a mine-by-mine basis began to appear from different dates: lead from 1845; copper from 1845; tin and silver from 1852; zinc from 1854; arsenic and barytes from 1855; iron, manganese and tungsten from 1858; and fluorspar from 1874. In the early years there was undoubtedly some under recording and the number of the mines included in the annual listings usually increased noticeably as the Mining Record Office developed its procedures for collecting information. It should be noticed that this study does not systematically include material listed under sales of ore in stone, streamworks and foreshores.

For many counties, the Ownership and Management returns give a good indication of the years of activity at a mine, even when it was not producing and selling ore. These returns are derived from the List of Mines, which was appended to the back of the early Mineral Statistics and later published separately. They are normally available for non-ferrous mines from 1859 and iron mines from 1863. However, for some unknown reason, the Cornish section of the returns gave no regular details of the ownership until the mid-1870s and confined itself only to managers and agents. For many mines, ownership returns continued to be patchy well into the last quarter of the century. Careful examination of the Lists of Mines also reveals that major revisions were periodically conducted when unusually large numbers of mines suddenly disappeared from the returns. This suggests that they were not carefully edited for every edition and that they therefore continued to include some mines long after they had been suspended.

The Employment returns were also drawn from the List of Mines and provide a further check on the periods, level and type of activity at the mines. For example, a prospecting or developing working might show significant levels of employment even though there was little or no production or sales of ore. Similarly, a changing distribution of workers between underground and surface operations can give an idea of when ventures began to run down their mining operations and concentrate only on the redressing of spoil heaps. It should be remembered that many of the smaller mines at best provided only part-time employment for their labour force and that the same miners may have been counted several times over at different workings. The decision to publish detailed employment returns appears to have been left to the discretion of the local Mine Inspectors. For most Cornish mines this fortunately started at the relatively early date of 1878.