Core Shack › Hera
Hera
Polymetallic Zn-Pb skarn
In the Cobar Basin, orebodies go down rather than out — and this one is a good argument for it.
Drillhole viewer
Every hole GSNSW holds within 500 m of the deposit centre. Drag to orbit, scroll to zoom, tap a collar for its details. Names are masked.
Collars on a local grid in metres from the deposit centre. The white trace is surveyed; the rest are drawn vertical.
What the core actually looks like
Hyperspectral mineralogy and core photography from the Geological Survey of NSW National Virtual Core Library. Shortwave infrared, dominant mineral group per 250 mm interval.
Deep and narrow, by design of the basin
Hera sits in the Nymagee district on the eastern side of the Cobar Basin, and it shares the geometry that makes Cobar-style deposits distinctive: steeply plunging, laterally restricted, and vertically extensive. GSNSW logs the deposit shape as a sheet.
The drilling reflects it. Among the holes designed to test at depth here, the median hole is close to three times deeper than at any of the other four deposits in this Core Shack. You cannot find a deposit like this with a shallow grid; you have to commit to depth.
A genuinely polymetallic ore
Gold, copper, zinc, lead and silver all appear in the GSNSW record for Hera, and the ore mineralogy backs it up: chalcopyrite, galena, pyrite, pyrrhotite and sphalerite, with gold, cubanite and niccolite among the accessories.
Pyrrhotite is worth flagging. It is magnetic, it weathers distinctively, and its presence points to a reduced, sulphur-rich environment. Alteration is logged as silicic and chloritic, with gangue of chlorite, muscovite and quartz.
Ore texture is massive, mineralisation style is vein. Massive sulphide in a vein-hosted setting is a good visual target — but a poor guide to which metal dominates, because five of them are competing for the same space.
Two classifications, both defensible
Worth being upfront about: this deposit is described in more than one way. The Core Shack listing calls it a polymetallic Zn-Pb skarn. The GSNSW MinView record classes it as distal intrusion-related Cu-Au with an intermediate, porphyry-adjacent genesis.
That is not a mistake in either direction. Cobar-style deposits have been argued over for decades, and the disagreement is genuinely about how far the fluids travelled from their intrusive source. Both descriptions are shown on this page as they were supplied.
What this kind of deposit looks like
An idealised model of the deposit type, built from the GSNSW description — shape, structure, mineralisation style and alteration. Drag it around.
What to look for in the tray
- Massive sulphide texture — and the fact that it cannot tell you which of five metals is carrying the value.
- Pyrrhotite: bronze, tarnishing, and magnetic. Bring a magnet.
- Vein margins and chloritic alteration against the host.
Grade guessing competition
Have a crack at the Hera tray
Running across both days at the Geological Survey of NSW booth — booths 20 and 21, Exhibit Room B.
- Look at the core. Prospect and deposit type are on the card; hole ID and assays are not, on purpose.
- Write your estimate on an entry slip at the booth. There is a category per commodity.
- Entries are open day 1 and day 2.
- GSNSW hold the assays until the prize presentation on day 2. A bottle of wine per category, supplied by the conference committee.
The GSNSW record
Straight from the Geological Survey of NSW mineral occurrence database, reproduced as supplied.
- District
- Nymagee
- Deposit size
- Very large
- Major commodities
- Au, Cu, Zn, Pb
- Minor commodities
- Ag
- Ore mineralogy
- chalcopyrite, galena, pyrite, pyrrhotite, sphalerite (celadonite, cubanite, gold, mackinawite, niccolite*, nontronite)
- Gangue
- chlorite, muscovite, quartz (albite, microcline, phlogopite)
- Alteration
- silicic, chloritic
- Ore texture
- massive
- Deposit shape
- sheet
- Mineralisation style
- vein
- Deposit class (NSW)
- Distal intrusion-related Cu–Au
- Deposit genesis (NSW)
- Intermediate (incl. porphyry)
When it was drilled
What is on this page, and what is not. Drillhole names are masked and shown as sequential identifiers. There are no assay results here, and no map coordinates — collar positions are plotted on a local grid in metres from the deposit centre, rounded to 5 m. That is deliberate: the competition only works if nobody can look up the answer from their phone while standing at the tray.
Everything else — deposit type, commodity, mineralogy, alteration, drilling history — is open-file information published by the Geological Survey of NSW.
Source: Geological Survey of NSW (MinView), supplied 21 August 2026. Reproduced with permission. MetaGeo sponsors the Core Shack at Mines and Wines 2026.