Under the Glass: Erdene's PEA runs 74% on inferred tonnes. Bonterra's goes negative at US$2,500 gold

Three economic studies and resource updates landed this week. As in last week's comparison, the questions are the same: what price is assumed, and how much of the plan sits on inferred material.

Erdene, Zuun Mod: three quarters inferred

Erdene Resource Development (TSX: ERD) released a PEA for its Zuun Mod molybdenum-copper project in Mongolia on October 14.

• After-tax NPV (8%): US$745 million at US$25 molybdenum and US$5 copper
• At spot prices of US$33 molybdenum and US$6.50 copper: US$2.0 billion
• IRR: 16.1% base, 27.8% at spot
• Initial capital: US$686.8 million, including US$176.7 million of contingency
• Mine life: 34 years at 25 million tonnes a year

The release states that about 74% of the PEA's plant feed is inferred. During the six year payback period the figure is about 16%, so the early years lean on better defined material. The base case NPV is only about 1.1 times the initial capital, by the company's own measure.

Bonterra, Barry: priced at US$3,500 gold

Bonterra Resources (TSXV: BTR) published a PEA for its Barry project in Quebec on October 14.

• After-tax NPV (5%): C$665 million at US$3,500 gold
• At US$4,100 gold: C$976 million
• Initial capital: C$118.7 million, with toll milling at a nearby plant
• Production: about 87,097 ounces a year over 7.2 years, per the table

The sensitivity table is the useful part. At US$3,000 gold the NPV is C$397 million. At US$2,500 it falls to C$71 million, and turns negative at some exchange rates. With capital and operating costs 40% higher, the NPV is negative. The plan includes inferred material, but the release does not say how much.

Epic Gold, Hawkins: all inferred

Epic Gold (CSE: EPG) reported a first resource of 440,400 ounces at 0.98 g/t for the McKinnon deposit at its Hawkins project in Ontario. All of it is inferred. The release says no economic study has been completed.

Xtra-Gold, Kibi: 11% outside the lease

Xtra-Gold (TSX: XTG) updated its Kibi resource in Ghana to 1,404,900 indicated ounces at 1.12 g/t, plus 180,800 inferred ounces. Of the indicated ounces, 156,100 sit in a Buffer Zone outside the Apapam mining lease. The company is "awaiting formal approval of the extension/renewal" and says there is "no assurance that such approval will be granted." The release does not state the gold price used.

Why it matters

Gold traded at about US$4,182 on October 13, so Bonterra's base case is conservative on price. Erdene's base case is conservative on price too, but most of its tonnes have not yet been drilled to the confidence a bank needs.

Sources: Erdene, October 14, 2026; Bonterra Resources, October 14, 2026; Epic Gold, October 8, 2026; Xtra-Gold, October 13, 2026. Gold price: Fortune, October 13, 2026.