Mining investor glossary

Every term you'll meet in an ASX gold or copper announcement, in plain English. Each analysis on DrillScore uses these words the same way.

AISC (all-in sustaining cost)

What it costs a producer to mine and sell an ounce of gold, including sustaining capital and overheads, usually in A$/oz. A producer's margin is roughly the gold price less its AISC. Reading a quarterly.

Appendix 5B

The quarterly cash flow report ASX explorers must file: cash, spending, financing facilities and, at item 8.7, the estimated quarters of funding left. Appendix 5B explained.

Assay

A laboratory measurement of how much metal a sample contains. Results are "pending" until the lab reports.

AuEq / CuEq (metal equivalent)

A single grade that converts several metals into one, using assumed prices and recoveries. The ASX's position is that equivalents aren't appropriate without metallurgical recovery information. Metal equivalents explained.

Competent person

The qualified, experienced professional (a member of an approved body such as the AusIMM) who takes responsibility for exploration results, resources or reserves under the JORC Code.

Cut-off grade

The lowest grade counted when an interval is calculated. A low cut-off makes long intervals; a high one makes short, rich ones.

Diamond drilling (DD)

Drilling that recovers a solid cylinder of rock (core). Slower and dearer than RC, but the best samples and geological information.

Dilution (capital)

When a company issues new shares, each existing share owns a smaller slice. A placement adding 20% more shares dilutes holders by about 17%. Raisings explained.

Down-hole width

The length of an interval along the drill hole. It overstates the true thickness of the mineralisation unless the hole crosses it at right angles. True vs down-hole width.

Ends in mineralisation

The hole stopped while still in mineralised rock, so the interval could be longer.

EV/oz

Enterprise value divided by resource ounces: a rough way to compare what the market pays for each ounce in the ground. Resources vs reserves.

g/t (grams per tonne)

The usual unit of gold grade: grams of gold in each tonne of rock. 1 g/t is the same as 1 ppm.

Gram-metres (g-m)

Down-hole width (m) x gold grade (g/t). One number that rewards both thickness and richness. Over 50 is good, 100-200 really good, 200-500 excellent, beyond that stellar. Gram-metres explained - calculator.

Including

A richer sub-interval inside a longer one ("40m at 2g/t including 3m at 15g/t"). Smearing.

Infill drilling

Holes drilled between earlier ones to improve confidence in a known deposit - as opposed to extension (step-out) or discovery drilling.

Inferred / Indicated / Measured

The three confidence levels of a JORC Mineral Resource, from least to most certain.

JORC Code

The Australasian code for reporting exploration results, Mineral Resources and Ore Reserves, which ASX-listed companies must follow.

JORC Table 1

The checklist appended to a JORC report: section 1 sampling techniques, section 2 reporting of exploration results, sections 3 and 4 resources and reserves. JORC Table 1 explained.

Mineral Resource

A concentration of mineralisation with reasonable prospects of eventual economic extraction, estimated under the JORC Code.

Nugget effect

Gold's habit of occurring in coarse particles, so two samples a metre apart can assay very differently. It makes high-grade intervals less repeatable.

Ore Reserve

The part of a Measured or Indicated Resource that is economically mineable after a study - Probable or Proved.

%-metres

Down-hole width (m) x copper grade (%) - the copper equivalent of gram-metres.

Placement

New shares sold to selected (usually institutional) investors, often at a discount, sometimes followed by a share purchase plan (SPP) for retail holders.

Porphyry

A large, usually lower-grade copper-gold deposit formed around an intrusion. Porphyry intercepts are long (hundreds of metres) at grades often under 1% Cu.

Price sensitive

An announcement the company has marked as able to materially move its share price.

RC (reverse circulation) drilling

Fast, cheaper drilling that returns rock chips rather than core.

Smearing

When one rich metre supplies most of a long interval's metal, making the whole interval look better than it is. DrillScore flags it when one sub-interval carries 70%+ of the metal-metres.

Step-out

A hole drilled beyond the known mineralisation to test whether it extends.

True width

The actual thickness of the mineralised zone, measured at right angles to it.

Visual estimate

A description of mineralisation from what the geologist sees (for example "5% chalcopyrite") before assays. The ASX discourages them. Visual estimates.

XGD

The S&P/ASX All Ordinaries Gold index of ASX-listed gold companies - the benchmark DrillScore compares price reactions against. Today's XGD.