Probability and Statistics - Geomathematics: Theoretical Foundations, Applications and Future Developments - page 67

Table 2.4 Classical example of 118 zinc concentration values (in per cent) from Pulacayo Mine,
Bolivia (original data according to de Wijs 1951 )
17.7, 17.8, 9.5, 5.2, 4.1, 19.2, 12.4, 15.8, 20.8, 24.1, 14.7, 21.6, 12.8, 11.9, 35.4, 12.3, 14.9, 19.6, 10.6,
15.1, 15.6, 9.3, 8.1, 13.5, 30.2, 29.1, 7.4, 12.3, 13.6, 9.5, 13.1, 27.4, 8.8, 11.4, 6.4, 27.4, 8.8, 11.4, 6 .4,
11.0, 11.4, 14.1, 20.9, 10.8, 15.3, 24.0, 12.3, 7.8, 9.9, 20.7, 25.0, 19.1, 13.1, 27.4, 15.2, 12.2, 10.1, 12.3,
16.7, 18.6, 6.0, 10.6, 11.3, 4.7, 10.9, 6.0, 7.2, 5.6, 8.9, 5.8, 8.9, 6.7, 7.2, 9.7, 10.8, 17.9 10.9, 13.7, 22.3,
10.2, 5.1, 13.9, 9.0, 10.6, 13.8, 6.5, 6.5, 10.6, 10.6, 23.0, 21.8, 32.8, 30.2, 30.8, 33.7, 26.5, 39.3, 24.5,
24.9, 23.2, 16.0, 20.9, 10.3, 22.6, 16.2, 22.9, 36.9, 23.5, 18.5, 16.4, 17.9, 18.5, 13.6, 7.9, 31.9, 14.1, 7.1,
3.9, 3.7, 22.5, 27.6, 17.3
Successive assays are for channel samples that were taken 2 m apart on the 446-m level of this
mine
Fig. 2.7 Simplified cross-section of Pulacayo dome with steeply dipping Tajo vein (After Pinto-
V ´ squez 1993 ). Mining level depths were measured downward from San L ´ on Tunnel (Source:
Agterberg 2012 , Fig. 2)
deposit and rock sampling in general. The geological setting of the Pulacayo Mine
and genesis of the sphalerite-quartz ore deposit are briefly described in a scientific
communication by Pinto-V ´ squez ( 1993 ).
The zinc values used by de Wijs ( 1951 ) are for channel samples cut at 2-m
intervals across the steeply dipping Tajo vein along a horizontal drift on the 446-m
level. This level depth was measured downward from elevation of the San L ´ on
Tunnel (Fig. 2.7 ). The 2.7 km long Tajo vein was discovered in 1883 and mined
until 1956. According to Ahlfield ( 1954 ), this “silver mine” had the largest annual
zinc and second largest annual silver production in Bolivia. On average, the Tajo
vein was 1.10 m thick with ore containing 14 % zinc and 0.1 % silver. Relative
sphalerite (zinc sulphide) content increased downward in the orebody. According
to Turneaure ( 1971 ) the age of the Tajo vein was Neogene, probably as young as
Pliocene. Figure 2.8 shows ore minerals in Pulacayo massive sulphide at