SOUTH CROFTY MINE LONG SECTIONS

South Crofty Mine produced an Ore Reserve Document every six months. This document set out all the mineral reserves of the mine on a lode by lode basis. Each lode was divided into blocks, roughly 50 metres along lode by 30 metres down dip (although this could vary markedly due to a variety of geological or planning factors), which were coded according to how much confidence could be placed on the grade and tonnage within the block. Measured blocks (highest confidence) were sampled extensively from level exposures, raises, diamond drill intercepts and sludge drilling to give large number of samples to base the final grade calculation on. Indicated I and II and Inferred I and II blocks had progressively less information on which to base the block grade and were therefore lower confidence blocks. Ideally a block would be upgraded over time, from Inferred II to Measured, as development took place around it and more drilling information became available. All the block information was put onto a long section of each lode, which showed the block distribution and the position of stoped (work out, extracted) areas and pillars, etc. These sections were regularly updated to keep pace with stoping and new development.

The sections, and their accompanying data, were essential for planning the supply of tin to the processing mill, with blocks of different grade being 'blended' to give a consistent feed, of around 1.5% Sn, to the mill. Various blocks, within a 3 month cycle, would be earmarked for extraction and it was of prime importance that the grade and tonnage assigned to each block was as accurate as possible to ensure a steady supply of ore, at the right grade (too rich, or too poor, and the mill would become inefficient and valuable tin concentrate could be lost - contaminants such as wofram and arsenopyrite also had to be carefully monitored).

It is eventually intended to place all the 'electronic' sections (many lodes worked prior to 1985 were still on film sections and were not updated) of lodes current at the time of closure, on this page - watch this space!

In addition to the reserve sections, geological sections through the main shafts (Roskear, Robinson's and New Cook's Kitchen) were also produced as film copies. A new version of the New Cook's Kitchen and East Pool Engine Shaft sections are shown below; others are to follow.

This is a work in progress and it is intended that all the available sections will be added to the site as the original AutoCAD files are converted to Gif format.

Right Click on the links below (save target as) to download the A3 section of your choice.

New Cook's Kitchen Shaft Section

I drew this section through NCK Shaft in September 1997, using the 1:500 film level plans and plans of the surrounding mines/shallow workings. It took around 40 hours to complete and was originally input into AutoCAD (as were all of the Geology Departments drawings). In 2001 I converted the file into CDR format and produced this coloured version in 2003. The file is in its intended A3 size in GIF format - the file size is 2.27 MB.

East Pool Mine Engine Shaft Section

This section through East Pool Mine Engine Shaft was completed in September 1997, using the 1:500 film level plans and plans of the surrounding mines/shallow workings. Engine Shaft was one of East Pool's principal shafts until a major collapse in 1921 rendered it unusable. The shaft is located close to the restored engine house at Mitchell's Shaft (owned by the National Trust) - Mitchell's Shaft was also partially destroyed in the collapse and was never used again. The company began a new shaft, Taylor's Shaft, in the northern part of the sett (the preserved engine house here, by Morrison's supermarket, is also owned by the National Trust) and found some rich lodes at depth that gave it a new lease of life. After East Pool closed in 1945 the sett was bought by South Crofty; in the late 1980's exploration beneath the East Pool workings lead to the discovery of the North Pool Zone (NPZ) - a complex replacement/lode/pegmatite series of bodies, that were a major producer of rich tin ore up until the mines closure in 1998. This drawing took around 40 hours to complete and was originally input into AutoCAD; in 2006 it was converted into a CDR drawing. The file is in its intended A3 size in GIF format - the file size is 528 KB.

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This page last updated on 27/06/2006