- used in single vein-type deposits
(e.g. gold-bearing quartz veins)
- channel & chip sampling was
conducted at 3-6 ft intervals along
the openings (drives, winzes, raises)

Tonnage (Old Style)

(area block)(thickness vein)(S.G.)

Delaunay Triangulation

Triangular Method

Tonnage (Triangular Method)

Volume=(area-triangle)(thickness)
Tonnage=(Volume)(S.G.)

Area of Triangle

Square/Rectangle Method

for flat type/near surface
deposits (bauxite,laterite)
- drill holes are at the centers

Polygonal Method

for flat type/near surface deposits
(bauxite,laterite)
- perpendicular bisectors are drawn
between every drill hole; areas are
planimetered/calculated

Contour/Isopach/Isograde Method

- for flat type, low-dipping disseminated
deposits

Isolines

constructed by interpolation
between points of known values
that assume a gradual
uninterrupted change from one
point to another

Isopachs

thickness of contours

Cross-Section Method

estimates a block of ground that is
bounded between regularly spaced
sections

Random Stratified Grid (RSG) Method

regular grid of a suitable size and an
orientation is adjusted on a set of drill
holes
- trial and error; until, at least one
sample value falls per grid panel.

Longitudinal Vertical Section (LVS) Method

divided into subblocks

Regionalized variable” theory

spatial relationships
between sample values, thickness, or any geological phenomena
showing intrinsic dispersion

theory of regionalized variables states that

t natural phenomena
are characterized by a distribution in space of one or more variables

Geostatistics

for mapping of surfaces from limited sample data and the
estimation of values at unsampled locations

Semivariance

Used to express the degree of relationship between the
points on a surface

Kriging

Named after D.G. Krige
- an optimal spatial interpolation technique that uses the
semivariogram in calculating estimates of the surface at grid
nodes

Simple Kriging

- there is an assumption that the mean is both constant and known (making it the most restricted form of kriging

Ordinary Kriging

applicable to samples with constant, but unknown
mean (no trend)
- most general and widely used