Workshop on the Establishment of a Geological Model of ...

Recalling Mr. de Souza’s presentation, Mr. de L’Etoile said that station data had been used for the
resource model. He emphasized that the original samples had not been used. He said that stations were
made up from the data for three or more samples, depending on the block in which they were found and that
samples were collected by each pioneer investor, using their own sampling and grouping protocols. All in all,
he concluded, that the data comprising 2,785 stations, with coordinates, abundance and metal grades
comprised a fair amount of information. He noted that, while he would be very happy to assess a mine or an
exploration project on land with 2,000 data samples, in this case, the data was spread over 4,000,000 sq. km.
Station density
Station density
Example: Block 22
348 stations in 90,000 km 2
Each station covers 260 km 2
(approx. 1 station every 1½1
square
cell)
Each square cell is 12.5km by
12.5 km
The “+” signs represent
stations
262.5 km
With regard to the sampling grids used by the
different pioneer investors, Mr. de L’Etoile recalled
that Mr. de Souza had said that the blocks contained
different sampling grids. Using Figure 25, Mr. de
L’Etoile provided an illustration of the relative density
of samples in each block. He observed that, as was
readily seen, the number of samples in each block
showed considerable variation. For example, he
noted that block 8 contained 4 stations and that block
22 contained 348 stations.
Figure 25
Station density
• The number of stations varies greatly per block from 4
(B8) to 348 (B22).
• Station density
in stations per km2:
Relative station density per block
In addition, Mr. de L’Etoile pointed out that
block 22, with a total of 348 stations covered a 19,000
sq km. area. He said that each station therefore
represented an area of 216 sq. km. Using Figure 26,
he illustrated the situation with respect to block 22.
• Block 15 has highest
sample density
Figure 26
14
13
12
11
10
15
9
8 7 6 5
4
16 17
18
19
20
21
22
23
24
1
3
2
With regard to Figure 26, Mr. de L’Etoile
pointed out that the grid size was 12.5 x 12.5 km (a
cell), the plus signs in the diagram are where the
actual stations are to be found, and that on average
the data comprise one station per one‐and‐a‐half
square cells. He further pointed out that the situation
was equivalent to having only one sample per mine
on land to work with.
Through Figure 27, he described station statistics. He said that these were the average depth, the
content of manganese and abundance values for each block and that the statistics revealed the presence of
outliner blocks, such as block 23, which had a higher average.
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