Australian emeralds: the forgotten deposits of the continent

Australia is a recognized producer of gems. It long dominated the opal market, produces sapphires in quantity, and above all supplied the world with its pink diamonds, thanks to the Argyle mine, closed in 2020 after single-handedly defining an entire segment of the colored diamond market.

On emerald, the record is quite different. The deposits exist, they are numerous, they have been worked on and off for more than a century. But gem-quality production has remained marginal, and Australia does not appear in any producing-country ranking that matters.

The reason comes down to three words. Quality, profitability, access. A large share of the material extracted is pale, heavily included, or too small. The deposits lie in remote desert areas, where logistics costs quickly exceed the value of what comes out of them. And the history of these mines is a succession of bankruptcies, speculation scandals and aborted restarts.

One site in the east, in the highlands of New South Wales, and three in the west, scattered across the vastness of Western Australia.

The story of the Australian emerald begins in 1890, by chance, as so often. A school buildings inspector on his rounds, D. A. Porter, prospects an old abandoned tin claim in the New England district, in northeastern New South Wales. He finds green crystals there. The nearby locality is then called Vegetable Creek; it would later take the name Emmaville.

The Emerald Proprietary Company sets about working the site. Over some twenty years, the region yields more than 53,000 carats of beryl and emerald, roughly ten kilos. The figure looks considerable until the essential point is added: the proportion of gem quality is low. Most of the crystals are pale, and the bulk of the mining ends up targeting beryl as beryllium ore rather than as a gem.

Attempts resume in waves, with no lasting success. Commercial mining is restarted at Torrington in the early 1990s, then abandoned for want of sufficient volumes.

The curiosity of Fielders Hill

The Fielders Hill site produces a singular material. The emerald does not form a homogeneous crystal there: it appears as clearly defined green zones inside crystals of colorless beryl.

That changes everything for a lapidary. Cut perpendicular to the crystal axis, the stone gives an emerald of classic appearance. Cut parallel to that axis, it gives a striped stone, alternating green and colorless bands. A gemologically unusual object, with no real market, but one that says everything about the capricious nature of these deposits.

This is the country's most important deposit. Discovered by chance by a prospector in the early 20th century, the sources hesitating between 1909 and 1912, the Poona district gathers thirteen mines within a radius of two and a half kilometers. The emeralds form there near pegmatite veins, in biotite and phlogopite schists.

The main mine, known as Aga Khan, has produced more than 23,000 carats since its discovery. Here again, the statistic hides a less flattering reality: a large share of that material is pale and of low commercial value.

A deposit 2.7 billion years old

Poona holds a remarkable title. Dating of its gems places their crystallization between 2.66 and 2.71 billion years ago, which makes it one of the oldest known emerald deposits on Earth. By way of comparison, Colombian emeralds are geological newborns, formed a few tens of millions of years ago.

A history of bankruptcies

The working of Poona is a textbook case of mining failure. Operations are interrupted by the First World War, then by financial difficulties. Speculation scandals and economic strains lead to successive restructurings and to requests for tax relief from the Australian government to keep the operation afloat. A restart is attempted after the Second World War under the name Aga Khan Deep Mine. The area remains a low-profitability site, worked by a succession of leaseholders who never manage to break even.

Menzies and Riverina, the roadside deposit

The Menzies emeralds, also called Riverina or Wonder Well, were discovered in the early 1970s in the most prosaic of circumstances, by workers who were building the Riverina-Mount Ida Road in 1972. The nearest town, Kalgoorlie, lies 200 kilometers to the south and owes its reputation to one of the largest gold mines in the country.

From 1972 to 2015, activity there is sporadic, leaving behind abandoned shafts and heaps of debris. Nine emerald-bearing veins spread over about 1,800 meters have been recorded. The methods range from hand prospecting to excavators with sorting on a conveyor belt. The color, attributed to chromium and vanadium, runs from a moderately intense yellow green to a slightly vivid green, and quality stones exceeding 5 ct have been found there.

Wodgina and Curlew, the 2023 awakening

The country's most isolated deposit. The Curlew mine lies 120 kilometers south of Port Hedland, in the Pilbara, an arid region of extreme temperatures, largely uninhabited, with scarce infrastructure and difficult access.

Discovered in 1920, the mine only entered official operation in 1970. It then went through several abandonments, sometimes lasting decades, before a resumption of production reported in 2023. The Wodgina area counts seven mines within a small perimeter, poorly documented, whose current status remains uncertain and which are hard to confirm as ever having produced significant quantities of gem quality.

Paradoxically, it is from there that the finest recently analyzed stones come. Curlew emeralds show slightly intense bluish green hues, a fine color and a remarkable brilliance that make them suitable for fine jewelry. The number of samples remains too small to generalize, but this small-scale artisanal production is considered promising.

Recognizing an Australian emerald is difficult, and for an interesting reason: most of its inclusions are found in many other deposits around the world. Two markers, however, stand apart.

Iron, the marker of a schist-hosted deposit

UV-Vis-NIR spectrometry reveals a high iron content in Curlew emeralds, with a characteristic absorption band around 810 nanometers. This is the classic signature of schist-type deposits, as opposed to iron-poor deposits such as those of Colombia, Musakashi in Zambia or Davdar in China.

This iron content also explains the hue of these stones. Iron cools the green and pulls it toward the bluish, a very different result from the warm green of the Colombian stones that can be seen at the Muzo emerald museum.

An unexpected inclusion

One detail deserves to be flagged, because it illustrates the limits of origin determination. A well-formed multiphase inclusion, containing six halite or sylvite crystals and two gas bubbles, was observed in a Torrington emerald. Yet this type of very salt-rich inclusion is considered all but exclusive to Afghanistan and the Panjshir valley.

The lesson is a useful one: no single criterion is enough to establish an origin. An inclusion reputed to be typical of one country can turn up on the other side of the world. Only the combination of inclusions, spectrum and trace element chemistry allows a serious conclusion.

Let us be clear: you will hardly find any. These stones almost never circulate in European trade channels, and nearly all of the historic production went into mineralogical collections rather than into jewelry.

If you do come across one, it will probably belong to one of these two categories.

The Australian emerald appears in no production ranking, and yet the first Emmaville crystals date from 1890. A certified Australian emerald remains today a collector's piece more than a jewelry standard, which explains how rare the stones are on the French market.