NI 43-101 Preliminary Economic Assessment - Verde Potash

Verde Potash Plc 12-3
Cerrado Verde Project
NI 43-101 Preliminary Economic Assessment
12.1.4 Variography
Introduction
Variography is used to describe the spatial variability or correlation of an attribute. The spatial
variability is traditionally measured by means of a variogram, which is generated by determining
the averaged squared difference of data points at a nominated distance (h), or lag (Srivastava and
Isaacs, 1989). The averaged squared difference (variogram or v(h)) for each lag distance is
plotted on a bivariate plot, where the X-axis is the lag distance and the Y-axis represents the
average squared differences (v(h)) for the nominated lag distance.
Several types of variogram calculations are employed to determine the directions of the
continuity of the mineralization:
Traditional variograms are calculated from the raw assay values;
Log-transformed variography involves a logarithmic transformation of the assay data;
Gausssian variograms are based on the results after declustering and a transformation to a
Normal distribution;
Pairwise-relative variograms attempt to 'normalize' the variogram by dividing the
analyses; and
Correlograms are 'standardized' by the variance calculated from the sample values that
contribute to each lag.
Fan variography involves the graphical representation of spatial trends by calculating a range of
variograms in a selected plane and contouring the variogram values. The result is a contour map
of the grade continuity within the domain.
The variography was calculated and modeled in the mining planning software, Gemcom Surpac
Software. The rotations are tabulated as input into Gemcom Surpac Software (geological
convention), with X representing the bearing, Y representing dip and Z representing plunge. Dip
and dip direction of major, semi-major and minor axes of continuity are also referred to in the
text.
Grade variography was generated to enable grade estimation via OK. Interpreted anisotropy
directions correspond well with the modeled geology and overall geometry of the interpreted
domain. The results are show in Table 12.1.4.1.
Table 12.1.4.1: Cerrado Verde Deposit Unweathered and Weathered Mineralized Domain
Variogram Models
K2O
Nugget
(CO)
Bearing
Rotation Structure 1 Structure 2
Dip Plunge
Sill 1
(C1)
Major
Range (m)
Semi-
Major Minor
Sill 2
(C2)
Major
Range (m)
Semi
Major Minor
Low Grade 0.21 180 -10 0 0.34 200 100 16.53 1.20 400 200 33.06
High Grade 0 21 180 -10 0 0.34 200 100 16.53 1.20 400 200 33.06
SRK Consulting (U.S.), Inc. September 16, 2011
Cerrado Verde_NI 43-101 PEA_343500.020_007_KG