Alto Metals begins drilling ‘long forgotten’ high-grade gold mine
Alto Metals says historical drill results highlight “significant” high-grade gold remains below the shallow Oroya pit.
The Oroya gold deposit was discovered in 1903, mined until 1920, revived in the 1990s and then abandoned again — and now Alto Metals (ASX: AME) is drilling there, which is the first work on the deposit in more than 15 years.
A maiden 2,000m reverse circulation drilling program is underway at the site, located just 500m east of Sandstone township.
The Oroya mine, within Alto’s Sandstone project in Western Australia, produced 220,000oz of gold at 16.5 grams per tonne up until 1920 from underground operations and then between 1994-95 the former Herald Resources mined it as an open pit, recovering 25,000oz gold at 2.3g/t.
Oroya considered an ‘outstanding’ gold target
Alto says historical results highlight that “significant” high-grade mineralisation remains beneath the open pit, which was mined to only 60m depth.
The company adds that mineralisation continues along strike and down dip of the underground workings of the main reef.
Historical assays comprise 23m at 6.2g/t gold, including 2m at 55.9g/t gold; and 8m at 17.9g/t gold, including 1m at 137g/t gold.
Mineralisation from these intercepts begins at 87m and 69m down hole, respectively.
Alto managing director Matthew Bowles said drilling is designed to test both plunge and strike extensions of the Sandstone Reef along with the unmined Juno Reef to the west.
He said that the company is excited to be drilling this “long forgotten” mine.
Drilling will also test the historic Hacks mine
Drilling will target extensions of the Sandstone Reef mineralisation to the northwest, beyond the north end of the open pit.
It will also test extensions to the south, and down dip to the west, which have not been adequately explored, the company said.
Alto is also reviewing the historic Hacks mine at its Sandstone project.
Hacks, also discovered in 1903, was mined in several periods, but between 1905 and 1914 it paid a total of £243,718 to shareholders in dividends, equivalent to A$30.3 million in today’s money.
In regards to Oroya, the company notes that the potential for remaining mineralisation is underlined by the fact that historical underground operations focused only on “bonanza-style” gold, as did the 1990s open pit mine, which had to cope with a gold price down to US$384/oz.