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Erdene Commences Drilling at Dark Horse GOLD Prospect

Exploration Programs

TSX: ERD | MSE: ERDN

www.erdene.com 1 [email protected]

ERDENE COMMENCES DRILLING AT DARK HORSE GOLD

PROSPECT

Press Release

Halifax, Nova Scotia

2023.06.08

Erdene Resource Development Corporation (TSX: ERD | MSE: ERDN) (“Erdene” or the

“Company”) is pleased to announce commencement of exploration at the Dark Horse

Gold prospect, located approximately two kilometers north of its Bayan Khundii Gold

Project in the Khundii Minerals District (the “District”) in southwest Mongolia.

Quotes from the Company

“Since discovery in early 2021, Erdene has defined a 1.5 kilometre mineralized trend at

the Dark Horse Mane prospect,” said Peter Akerley, Erdene’s President and CEO. “The

current program will test a number of near-surface targets in the 20 square kilometer

greater Dark Horse prospect area, outside the main mineralized zone, that have the

potential to host high-grade gold mineralization.”

“Located just two kilometres north of the main Bayan Khundii gold deposit, ore from Dark

Horse is expected to provide flexibility in managing high-grade ore feed at the Bayan

Khundii gold processing plant,” continued Mr. Akerley. “Growing high-grade gold

resources at Dark Horse will strengthen the already strong economics of the Bayan

Khundii gold project, that is slated to break ground in the coming weeks.”

Program Overview

The Q2 2023 greater Dark Horse exploration program includes 18 shallow holes totaling

approximately 1,000 metres to test for near-surface oxide related gold mineralization

similar to the Dark Horse Mane deposit. In conjunction with the diamond drill program,

the Company is also completing a gradient array IP geophysical survey covering a 9

square kilometre area, over the core of the greater Dark Horse prospect.

The target area (see Dark Horse Prospects Plan Map attached in release) exhibits

extensive gold and indicator element mineralization over several kilometres along NE

trending structures and their intersections with N-S faults, parallel to the Dark Horse Mane

structure. Results from this program will establish priority targets for a larger program,

scheduled to start in Q3, following the receipt and interpretation of results from the current

drilling and geophysical programs.

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Dark Horse Prospect Overview

The greater Dark Horse prospect (approximately 20 square kilometres) is located in the

northern portion of the Khundii mining and Ulaan exploration licenses and is characterized

by elevated gold in soil anomalism with multiple surface rock-chip, trench and drill core

samples assaying greater than 1 g/t gold. Trace element anomalism, geophysical

anomalies related to alteration and mineralization, structures interpreted to represent

conduits for mineralizing fluids, and alteration signatures supporting an epithermal

mineralization model characterize the greater Dark Horse prospect area. To date , the

Company has completed 24,092 metres of drilling in 218 holes ranging in vertical depths

from 8 to 318 metres within the greater Dark Horse prospect portion of the Khundii mining

license, including 28 holes totaling 2,355 metres in 2022.

Most of the drilling to date has been focused on the Dark Horse Mane discovered in early

2021. Erdene discovered Dark Horse Mane, 2 kilometres north of the Bayan Khundii

deposit, when initial drilling returned 6.0 g/t gold over 45 metres, beginning 10 metres

downhole, including 8 metres of 27.1 g/t gold (AAD-58). Drilling over the past year has

defined a 1.5-kilometre trend of alteration and gold mineralization within the Dark Horse

Mane prospect that remains open along strike to the north and south, and at depth.

Highlight interceptions at Dark Horse Mane since the initial discovery include:

• AAD-126: 30 metres of 5.6 g/t gold, beginning 10 metres downhole, including 24.1

g/t over six metres, starting 26 metres downhole

• AAD-137: 24.5 metres of 9.4 g/t gold beginning 1.5 metres downhole, including

13.5 metres of 16.1 g/t gold

• AAD-138: 25 metres of 6.1 g/t gold beginning 18 metres downhole, including 8

metres of 17.1 g/t gold

• AAD-177: 23 metres of 11.4 g/t gold beginning 1 metre downhole, including 4

metres of 59.8 g/t gold within 8 metres of 32.2 g/t gold

• AAD-178: 15 metres of 42.8 g/t gold beginning 11 metres downhole, including 3

metres of 160.4 g/t gold within 5 metres of 123.5 g/t gold

• AAD-218: 12 metres of 20.2 g/t gold beginning at surface, including 6 metres 39.6

g/t gold

The Dark Horse Mane prospect is associated with a north-south trending, linear structural

corridor which intersects deep seated northeast trending transform faults, believed to be

a conduit for primary mineralizing fluids. The N-S structure has been traced over five

kilometres, from the southern portion of the Bayan Khundii deposit to the northern

extension of Dark Horse Mane. Gold mineralization is hosted within strongly altered

tuffaceous and volcanoclastic rocks, crosscut by quartz and quartz-hematite veins and

stockwork zones. The Dark Horse Mane shallow oxide zone begins at surface, hosting

supergene enriched gold zones with values up to 195 g/t over 1 metre and ranging in

thickness from 20 to 60 metres vertical depth with locally deeper oxidation along fractures.

The high-grade oxide body exh ibits strong continuity along a north -south strike.

Mineralization remains open along strike and at depth.

The near surface oxide gold zones discovered at Dark Horse Mane are the result of

oxidation of sulfide bearing epithermal veins and hydrothermal breccias within white mica

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altered host lithologies. Limited deeper drilling has intersected gold bearing epithermal

veins and associated white mica and sulfide alteration zones to a depth of up to 230

metres vertically, that remains open at depth. The gold mineralization near surface at

Dark Horse Mane is related to broader areas of structurally controlled alterat ion and

mineralization believed to be connected to feeder structures, distributing gold bearing

fluids over a wide area as these fluids approached the paleo surface. Evidence for these

feeder structures includes a series of exposed residual quartz lithocap s, associated

locally with increasing copper anomalism at depth , interpreted to predate the gold

mineralization. These lithocaps are distributed along dominant NE trending structures

believed to represent transform faults and potentially feeder conduits from a magmatic

porphyry source at depth. The highest-grade gold bearing oxide zones at the southern

end of the Dark Horse Mane are located proximal to the residual quartz lithocaps and

hosted within tuffaceous to porphyritic volcanoclastic units.

RC drilling in Q2 2022 identified several prospects within the greater Dark Horse area.

Multiple RC holes at East Mane, an 8-hectare area, 500 metres east of Dark Horse Mane,

returned anomalous gold (up to 0.22 g/t gold over 3 metres) and pathfinder elements

(antimony and arsenic). The East Mane area also exhibits structural and geological

similarities to high-grade Dark Horse Mane South mineralization.

About Erdene

Erdene Resource Development Corp. is a Canada-based resource company focused on

the acquisition, exploration, and development of precious and base metals in

underexplored and highly prospective Mongolia. The Company has interests in three

mining licenses and an exploration license in Southwest Mongolia, where exploration

success has led to the discovery and definition of the Khundii Minerals District. Erdene

Resource Development Corp. is listed on the Toronto and the Mongolian stock exchanges.

Further information is available at www.erdene.com. Important information may be

disseminated exclusively via the website; investors should consult the site to access this

information.

Qualified Person and Sample Protocol

Peter Dalton, P.Geo. (Nova Scotia), Senior Geologist for Erdene, is the Qualified Person

as that term is defined in National Instrument 43-101 and has reviewed and approved the

technical information contained in this news release. All samples have been assayed at

SGS Laboratory in Ulaanbaatar, Mongolia. In addition to internal checks by SGS

Laboratory, the Company incorporates a QA/QC sample protocol utilizing prepared

standards and blanks. All samples undergo standard fire assay analysis for gold and ICP-

OES (Inductively Coupled Plasma Optical Emission Spectroscopy) analysis for 33

additional elements. For samples that initially return a grade greater than 5 g/t gold,

additional screen-metallic gold analysis is carried out which provides a weighted average

gold grade from fire assay analysis of the entire +75 micron fraction and three 30-gram

samples of the -75 micron fraction from a 500 gram sample.

Erdene’s drill core sampling protocol consisted of collection of samples over 1 or 2 metre

intervals (depending on the lithology and style of mineralization) over the entire length of

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the drill hole, excluding minor post-mineral lithologies and un-mineralized granitoids.

Sample intervals were based on meterage, not geological controls, or mineralization. All

drill core was cut in half with a diamond saw, with half of the core placed in sample bags

and the remaining half securely retained in core boxes at Erdene’s Bayan Khundii

exploration camp. All samples were organized into batches of 30 including a commercially

prepared standard, blank and either a field duplicate, consisting of two quarter -core

intervals, or a laboratory duplicate. Sample batches were periodically shipped directly to

SGS in Ulaanbaatar via Erdene’s logistical contractor, Monrud Co. Ltd.

Reported intervals are apparent thicknesses, i.e., downhole widths. The current Bayan

Khundii drill holes (reported in this release) are all dipping from 45 to 60 degrees and

oriented to intersect SW dipping WNW trending gold bearing veins. Additional study is

required to confirm true widths. Reported grades for intervals are weighted averages

based on length of sampling intervals. No top cut has been applied; however, all intervals

greater than 10 g/t gold and 100 g/t gold are reported individually for clarity

Forward-Looking Statements

Certain information regarding Erdene contained herein may constitute forward-looking

statements within the meaning of applicable securities laws. Forward-looking statements

may include estimates, plans, expectations, opinions, forecasts, projections, guidance, or

other statements that are not statements of fact. Although Erdene believes that the

expectations reflected in such forward-looking statements are reasonable, it can give no

assurance that such expectations will prove to have been correct. Erdene cautions that

actual performance will be affected by a number of factors, most of which are beyond its

control, and that future events and results may vary substantially from what Erdene

currently foresees. Factors that could cause actual results to differ materially from those

in forward-looking statements include the ability to obtain required third party approvals,

market prices, exploitation, and exploration results, continued availability of capital and

financing and general economic, market or business cond itions. The forward-looking

statements are expressly qualified in their entirety by this cautionary statement. The

information contained herein is stated as of the current date and is subject to change after

that date. The Company does not assume the oblig ation to revise or update these

forward-looking statements, except as may be required under applicable securities laws.

NO REGULATORY AUTHORITY HAS APPROVED OR DISAPPROVED THE

CONTENTS OF THIS RELEASE

Erdene Contact Information

Peter C. Akerley, President and CEO, or

Robert Jenkins, CFO

Phone: (902) 423-6419

Email: [email protected]

Twitter: https://twitter.com/ErdeneRes

Facebook: https://www.facebook.com/ErdeneResource

LinkedIn: https://www.linkedin.com/company/erdene-resource-development-corp-/

N

KHUNDIIMINERALSDISTRICT PLAN MAP

Greater Dark Horse 2023 Exploration

Drill Testing Shallow High-Grade Gold Targets

GREATER DARK HORSE

ULAAN BAYAN KHUNDII

Gold ≥ 0.1 g/t*

Primary Target Structure

Anomalous Indicator*

(±Sb, As, Qtz Veining, Alteration)

Secondary Structure or Splay

*Based on drill result interpolation only

2000 m

DARK HORSE MANE

IP Gradient Array Survey