E2 Metals (ASX: E2M) has reported promising metallurgical results from its Mia gold-silver prospect in Argentina with a recovery rate of more than 90% gold using conventional cyanide bottle roll testing.
The test work was carried out in Santiago, Chile, on composite drill hole samples in oxide, transition and sulphide mineralisation.
High gold recoveries were achieved at both fine and coarse grind sizes.
E2 Metals added that cyanide consumption during the tests was “generally low”.
Silver mineralisation also amenable to recovery
In addition, silver mineralogy identified as electrum and acanthite (a silver sulphide) was shown to be amenable to both cyanide leaching and gravity recovery.
Mia is part of the company’s Conserrat project, which comprises a single title of 8,696 hectares within the Santa Cruz Province of Argentina.
The title is centred 130km northwest of local service town Puerto San Julian and some 30km west-northwest of AngloGold Ashanti’s (ASX: AGG) large Cerro Vanguardia mine.
Cerro Vanguardia is the largest epithermal vein field in the Santa Cruz province with historical and current resources estimated to be 8.9 million ounces of gold and 137Moz of silver.
Test work will now expand to other prospects
E2 Metals managing director Todd Williams says further studies are planned which will investigate silver recoveries via gravity concentration and cyanidation.
He was optimistic about the first round of gold recovery tests.
“These preliminary metallurgical results are encouraging and show that oxide mineralisation at Mia is free milling and amenable to a simple heap leach operation.”
Mr Williams added that metallurgical testing will continue in parallel to the current exploration drill program, and the company will expand the metallurgical test work to samples from other prospects.
Lower depths tend to be silver dominant
Silver recovery was not a primary target for this phase of metallurgical test work.
“Instead, a greater emphasis was placed on understanding silver mineralogy and deportment to allow targeted programs to be developed in future stages of the work.”
On the gold tests, the company states that gold mineralisation is best developed in the oxidised portions of the Lara vein structure at Mia.
Deeper sulphide mineralisation tends to be silver-dominant, and gold grades there range from 0.5 grams per tonne to 1g/t.
In the oxidised section, gold assayed returned at 2.9g/t (with 381g/t silver).