Chesapeake Announces Metallurgical Testwork Update
Chesapeake Announces Metallurgical
Testwork Update
Vancouver, British Columbia--(Newsfile Corp. - September 6, 2023) - Chesapeake Gold Corp. (TSXV:
CKG) (OTCQX: CHPGF) ("
Chesapeake
" or the "
Company
") is pleased to provide a metallurgical and
mineralogical update for its world-class Metates gold-silver project located in Durango State, Mexico.
Alan Pangbourne, CEO, commented, "We are very encouraged with the latest results from this phase of
metallurgical testwork.
A systematic, methodological approach individually testing several parameters
under different conditions is being undertaken in 42 columns.
The results have identified certain
parameters that provide the conditions where the leach technology oxidizes mineralization at a faster
rate than our previous testwork. Under these conditions, we believe the targeted oxidation curve will be
achieved and provide the foundation for preparing the pre-feasibility study early next year."
Metallurgical Testwork Program
Since our last update in September 2022 (NR04-2022), our metallurgical work has continued to
investigate various parameters to improve the oxidation rates of our sulphide leach technology.
The
focus has included investigating several ways to accelerate the oxidation kinetics and to understand how
to improve and optimize the oxidation rate.
Lab Photo with Over 40 Columns Currently Under Oxidation or Cyanide Leach
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The parameters tested during this stage of work include: (i) finer crushing sizes from ½" to ⅜" to ¼" and
the use of High Pressure Grinding Rolls ("
HPGR
") to produce a very fine crush at approximately 3mm;
(ii) varying reagent strengths; (iii) targeting different pH's; (iv) testing on/off irrigation; (v) applying other
oxidants; and (vi) varying air injection rates.
As illustrated in the lab photo above, over 40 columns are
currently under oxidation or cyanide leach.
Oxidation Rates for the Metates Massive Instrusive Samples
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The above graph illustrates the oxidation rates for the Metates massive intrusive samples and highlights
the improved oxidation rates relative to previously released column results.
The new conditions are
showing very encouraging oxidation rates, the Phase 3 columns have achieved an oxidation level of 15%
to 16% in just 60 days, which when compared to the initial sighter column is 50% faster and for the
Phase 2 columns over 300% faster.
These Phase 3 columns will be transitioned to cyanide leach once
they achieve the target oxidation above 35%.
Mineralogical Investigations
At the completion of the Phase 2 metallurgical testwork, a comprehensive mineralogical program was
initiated to analyze how the various sulphides were oxidizing. Twelve samples were taken from eight
Phase 2 columns (C2, C4, C5, C7, C10, C12, C14 and C16).
Samples were both post-oxidation or
post-oxidation and cyanide leach.
Of these 12 samples, a third were polished into thin sections for
observation through a reflected light microscope (3 samples), and the remaining were polished into
pucks for Scanning Electron Microscopy ("
SEM
") - Microprobe analysis (9 samples).
Within these nine
microprobe samples, 103 areas of interest were identified for optical observation and in total 990
energy dispersive x-ray spectrometer chemical analyses were conducted on these areas to determine
the minerals observed.
Figure 1a and 1b
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The mineralogical work identified several examples where the alkaline solution(s) had actively oxidized
and transformed the sulphide minerals present within the Metates host rocks.
Microprobe imaging of
sample 11 in Figure 1a shows an example of an iron sulphide marcasite mineral (another form of pyrite)
that has been altered completely from its original chemistry, but the radial form of the mineral remains
intact.
The sulphur content within this mineral has been stripped away and replaced by oxygen, forming
hematite, the same iron oxide that forms when iron rusts.
An example of an unaltered marcasite mineral
is illustrated in Figure 1b for reference
1
, evidencing the same radial growth of the crystals.
Sample 11 comes from column 12, which was an intrusive breccia sample from Metates that was
crushed to ½ inch, and the sample examined was the passing 35 mesh size fraction.
This sample had
been oxidized for 180 days with an alkaline solution prior to sampling for SEM microprobe work (no
cyanide leaching was performed at this stage).
This example highlights the breakdown of iron sulphide
minerals through the oxidative leach technology. The partially exposed precious metals locked within are
liberated and can be dissolved through the standard cyanide leach process typical of conventional oxide
heap leaching projects.
Figure 2
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Microprobe imaging of sample 7 in Figure 2 captures an example of another iron sulphide mineral that
was once pyrite, which is in the process of altering to hematite or limonite.
This image shows the
process of preferential mineral oxidation that has followed along the cleavage planes (structural
fractures) of the mineral.
Along these cleavage planes the sulphur from the pyrite has been stripped
away and replaced with oxygen, transforming these regions into iron oxides, whereas in the centers,
there are small core remnants of the original pyrite crystal.
Sample 7 is from column 12, which was an intrusive breccia sample from Metates that was crushed to ½
inch, and the sample examined was the passing 35 mesh size fraction.
This sample had been oxidized
for 180 days with an alkaline solution, and cyanide leached for 90 days prior to sampling for SEM
microprobe work.
This example further collaborates and shows another pathway in which the oxidative
leach technology breaks down the iron sulphide minerals and releases the precious metals locked
within.
Figure 3
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Microprobe imaging of sample 9 in Figure 3 provides another example of the oxidation of an iron
sulphide mineral that was once pyrite, now altering to hematite or limonite. This image captures the
periphery of the pyrite mineral being oxidized first, and a transition zone and digestion boundary are
clearly demarcated, creating a notable zonation.
Sample 9 is from column 4, which was a massive intrusive sample from Metates that was crushed to ½
inch, and the sample examined was the passing 35 mesh size fraction.
This sample had been oxidized
for 180 days with an alkaline solution prior to sampling for SEM microprobe work.
This example
highlights another pathway in which the oxidative leach technology breaks down the iron sulphide
minerals and releases the precious metals locked within.
Figure 4
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Finally, reflected light microscope imaging of sample 8 discovered a native gold particle in the form of
electrum, see Figure 4.
This identified electrum bleb is located within a pyrite crystal, and its existence
signifies the presence of native gold within the Metates system, which is in addition to the gold known to
be within the sulphide minerals.
Sample 8 is from column 16, which was an intrusive breccia sample from Metates that was crushed to ½
inch, and the sample examined was the passing 35 mesh size fraction.
This sample had been oxidized
for 180 days with an alkaline solution, and cyanide leached for 90 days prior to sampling for mineralogy
work.
Next Steps
Chesapeake will continue to advance the metallurgical program.
As the columns meet the oxidation
curve target and switch to cyanide leaching, additional columns will be loaded and tested to confirm the
improved oxidation rates.
At the completion of this process, the results will be released outlining the
oxidative curves and precious metal recoveries through cyanide leaching.
Once sufficient metallurgical
work is available, management plans to commence a pre-feasibility study to further de-risk Metates and
advance the project toward our goal of developing one of America's largest gold and silver deposits
2
.
In addition, the Company is actively seeking other sulphide gold deposits where the leach technology
can be applied to potentially unlock significant economic value.
Presently, Chesapeake remains well funded with almost C$24 million in cash and cash equivalents.
Qualified Persons
Dr. Art Ibrado, P.E., of Fort Lowell Consulting PLLC, is the independent qualified person responsible for
the scientific and metallurgical technical information in this news release in accordance with NI 43-101.
The qualified persons have reviewed and approved the contents of this release.
About Chesapeake
Chesapeake Gold Corp. is focused on the discovery, acquisition, and development of major gold-silver
deposits in North and South America. Chesapeake's flagship asset is the Metates project ("
Metates
")
located in Durango State, Mexico. Metates hosts one of the largest undeveloped gold-silver deposits in
the Americas
2
with over 16.77 million ounces of gold at 0.57 grams per tonne (g/t) and 423.2 million
ounces of silver at 14.3 g/t within 921.2 million tonnes in the Measured and Indicated Mineral Resource
category and a further 2.13 million ounces of gold at 0.47 g/t and 59.0 million ounces of silver at 13.2 g/t
within 139.5 million tonnes in the Inferred Mineral Resource category. See the technical report titled
"Metates Sulphide Heap Leach Project Phase I" dated January 13, 2023, and news release dated
February 23, 2023.
Chesapeake also has an organic pipeline of satellite exploration properties strategically located near
Metates. In addition, the Company owns 68% of Gunpoint Exploration Ltd., which owns the Talapoosa
gold project in Nevada.
For Further Information:
For more information on Chesapeake and its Metates Project, please visit our website at
www.chesapeakegold.com
or contact Alan Pangbourne or Jean-Paul Tsotsos at
or +1 778 731 1362.
Alternatively, join us at our webinar on Thursday, the 7
th
, at 11 am PST using the link below.
https://events.6ix.com/preview/64f77bcc7fb895bed6f7b424
Neither TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in policies
of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this news release.
Forward-looking Statements
This news release contains "forward-looking statements" within the meaning of Canadian securities
legislation. These include, without limitation, statements with respect to the strategic plans, timing and
expectations for the Company's exploration and drilling programs at the Metates Property, including
advancing the metallurgical test program, release of final results and preparing a pre-feasibility study.
Such forward looking statements or information are based on a number of assumptions, which may
prove to be incorrect. Assumptions have been made regarding, among other things: the reliability of
mineral resource estimates, the conditions in general economic and financial markets; the price of
gold and silver; availability and costs of mining equipment and skilled labour; timing and amount of
expenditures related to drilling programs; and effects of regulation by governmental agencies. The
actual results could differ materially from those anticipated in these forward-looking statements as a
result of risk factors including: the timing and content of work programs; results of exploration
activities; the interpretation of drilling and testing results and other geological data; receipt,
maintenance and security of permits and mineral property titles; environmental and other regulatory
risks; project cost overruns or unanticipated costs and expenses; and general market and industry
conditions. Forward-looking statements are based on the expectations and opinions of the Company's
management on the date the statements are made. The assumptions used in the preparation of such
statements, although considered reasonable at the time of preparation, may prove to be imprecise
and, as such, readers are cautioned not to place undue reliance on these forward-looking statements,
which speak only as of the date the statements were made. The Company undertakes no obligation to
update or revise any forward-looking statements included in this news release if these beliefs,
estimates and opinions or other circumstances should change, except as otherwise required by
applicable law.
1
Marcasite.
(2023, September 1). Encyclopædia Britannica.
https://www.britannica.com/science/marcasite#/media/1/364089/119889
2
Mexico's biggest undeveloped gold deposits. Bnamericas. Published Tuesday, November 24, 2020.
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