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VII-4
magnesium sulfates (such as kieserite), and "insolubles" (mostly clay).
These ore and mineral calculations were perfonned by the USGS for the P-Series
and AEC No.8, and by the individual mining companies when they reported drilling
results to the BLM. Therefore, the assay information entered into the database has been
adjusted for the mineral suite present at each specific ore intercept. A few spot checks of
these calculations were made, and found to :le correct.
What then was entered into the database was the percent in Kp units for sylvite
or langbeinite. These are considered to be the only two economic minerals present. The
usage of percent KzO rather than the true chemical equivalent of potassium (KCl for
sylvite or KzSO. ·2MgSO. for langbeinite) is a custom of the potassium fertilize: industry.
Ore intercepts. There are 11 known potash-bearing horizons in the Carlsbad
Potash Mining District. They are numbered in sequence upward. The 40 drill holes that
fonn the database encountered potash mineralization i:J all but the 1st, 6th, and 7th of
these horizons. While the principal economic deposit:; are only in the 4th and 10th ore
zone;. all known minerai intercepts were entered into the database, and the in-place tons
and grade were computed for each.
The drill records report the depths to tops, bottoms, and resulting thicknesses of
each ore intercept. This information was placed into the database. In a few instances,
John et al. (1978) reported double intercepts for a single ore bed when a lens of barren
halite divided the bed into two layers. Most notably this occurred in the 4th ore zone
intercept in hole P-21. This particular intercept was combined and corrected so that the
data input was 7.35 ft of 5.88% ~O as langbeinite. In all other cases the thicker
reported intercepts were always selected.
Mixed ores. It is common in this area of the Carlsbad Potash Mining District to
find ore that is a mixture of both sylvite and langbeinite. This is true for both the 4th and
10th ore zones in the vicinity of the WIPP Site. These mixed ores are being mined and
processed with economic success by one of the mining companies, !MC Fertilizer, a few
miles west and south of the WIPP Site.
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The BLM has used an "Equivalent Grade" for such ore mixtures. The calculation
IS as follows:
Langbeinite-dominant ores: Equiv. KIO = % KIO as langbeinite + 0.4 x % K 1 0 as
sylvite
Sylvite-dominam ores: Equiv. KIO = % ~O as sylVite + 2.5 X
% ~O as langbeinite
This 4: 1 ratio is based on a balance cif % ~O between the two minerals and their
sales value. The reserves of both the 4th and 10th ore zones were calculated using the
EquiValent Grade: langbeinite-dominant for the 4th and sylvite-dominant for the 10th.
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