Polymetallic Stock Calculator
Gold-copper-silver deposits handled as a single DCF with combined per-tonne revenue from all three commodities. Leave a commodity's grade at 0 to ignore it. Output compares a base-case and long-term price deck side-by-side.
When to Use This Calculator
Polymetallic deposits combine meaningful contributions from multiple metals into a single mine economics. Common examples:
- Gold-copper porphyries — Western Copper's Casino, Ivanhoe's Kamoa-Kakula, Freeport's Grasberg
- Gold-silver epithermals — MAG Silver's Juanicipio, Pan American's Dolores, Coeur's Palmarejo
- Silver-lead-zinc VMS — Skeena's Eskay Creek, Sandfire's DeGrussa
- Copper-silver strata — KGHM's Lubin, Sandfire's Matsa
How the Combined NAV Works
For each tonne of ore processed, revenue per tonne is the sum of each commodity's contribution:
rev/t = (Au_gpt × recovery × Au_price/oz) + (Cu_% × recovery × Cu_price/lb × 22.05) + (Ag_gpt × recovery × Ag_price/oz)
The same DCF, category weighting, and stage haircut then flows from that combined revenue-per-tonne number. This is the same revenue math used in industry feasibility studies — simplified to no tax, no royalties, no sustaining capex for V1.
Known Limitations (V1)
This calculator is a directional tool, not a replacement for a full engineering model. What it does not include:
- Corporate tax (add ~25-30% to opex for a rough proxy)
- Sustaining capex during operations — material in declining-grade operations
- Inflation adjustment — all numbers in nominal USD
- Royalty streams and NSR payments
- Debt servicing — the calculator assumes 100% equity financing
- Commodity-price hedges — hedged producers earn less upside than spot prices suggest
- Gold-copper-silver only — zinc, lead, and molybdenum (common in real polymetallic deposits) not included
- Two price benchmarks per commodity rather than four, to keep the form manageable
Do your own due diligence.
Read the company's 43-101 technical report, their most recent annual information form, and their insider-transaction filings before acting on any NAV estimate — including this one. Informational only; not investment advice. Full disclaimer →
Understanding Polymetallic Stock Valuations
Why Polymetallic NAV is Its Own Discipline
Polymetallic deposits are the most common type of real-world mine — pure single-commodity deposits are the exception, not the rule. A gold-copper porphyry like Western Copper's Casino or Ivanhoe's Kamoa-Kakula produces meaningful gold alongside the copper; a silver-lead-zinc VMS system like Eskay Creek produces all three commodities in economic quantities. Valuing these assets with a single-commodity calculator systematically understates their true worth — sometimes by 20-40% of the published NAV figure, depending on byproduct contribution. This calculator combines up to three commodities (gold, copper, silver) into a single discounted-cash-flow model that captures the full revenue stream from every tonne of ore processed.
How This Calculator Handles Combined Revenue
For each tonne of ore processed, the calculator sums the revenue contribution from each of gold, copper, and silver that you have provided non-zero grades for. Gold and silver grades are entered in grams per tonne and priced in $/oz; copper grade is entered in percent and priced in $/lb. Each commodity's contribution is the product of its grade, recovery, and price, converted to a revenue-per-tonne figure. The total revenue per tonne drives the DCF in the same way the single-commodity calculators work. Resource-category confidence weights (inferred 20%, indicated 50%, measured 75%, probable 85%, proven 100%) apply to the tonnage base, and a study-stage haircut (PEA 30% cut, PFS 15%, FS 0%) applies to the final per-share NAV.
Common Polymetallic Deposit Archetypes
- Gold-copper porphyries: Large-tonnage, low-grade. Typical grades 0.3-0.8% Cu with 0.2-0.5 g/t Au. Gold contributes 20-40% of revenue even though copper is the primary commodity. Casino, Kamoa, Cascabel.
- Gold-silver epithermal: Moderate-tonnage, higher-grade. Typical grades 2-10 g/t Au with 50-200 g/t Ag. Silver often contributes 15-30% of revenue. Juanicipio, Palmarejo, Dolores.
- Silver-lead-zinc VMS: Smaller-tonnage, polymetallic. Silver grades 100-500 g/t typical. Lead and zinc (not supported in this V1 tool) often contribute 40-60% of revenue. Skeena's Eskay Creek restart is a modern example.
- Copper-silver stratabound: Copper-dominant with silver credits of 20-80 g/t typical. KGHM's Lubin, the African Copperbelt's Zambian mines.
The Commodity-Correlation Risk
A polymetallic deposit looks diversified from a price-exposure standpoint, but the three commodities in this calculator (gold, copper, silver) are not as uncorrelated as investors assume. Gold and silver move together over multi-year windows because of their shared monetary driver layer. Copper and silver can move together when industrial demand surges. Gold and copper can both fall during a USD-strength episode. The calculator does not model this correlation — each commodity is treated independently — but the operator (and investor) is fully exposed to simultaneous drawdowns across all three. When evaluating a polymetallic name, test the NAV with a stressed low-price deck on all three commodities simultaneously as your downside-case scenario.
Reading the Output
Three rows, two columns. The gross NAV row assumes every tonne is measured-category quality with no study-stage risk. The category-weighted NAV row discounts for resource classification. The stage-adjusted NAV (highlighted in gold) applies both category and study-stage haircuts — the realistic read. The two columns are your Base-Case and Long-term price decks. The spread between columns tells you how much the deposit's value depends on commodity-price assumptions. A polymetallic deposit with a narrow spread is relatively robust across cycles; a deposit with a wide spread is more price-sensitive and requires a confident commodity-price view to own comfortably.