It said the data, geological compilation and reinterpretation had revealed "significant potential to add gold and silver ounces in unmined areas", citing historic drill results at AGB including 3m at 259.76g/t gold and 3,320.3g/t silver.
Benchmark said the AGB Zone was just 2km from the main resource expansion area at Lawyers and was under-explored and never fully mined.
The company is aiming for a 5 million ounce gold-equivalent resource at Lawyers after establishing a maiden 88,000oz gold and 4Moz silver resource last year.
The former Cheni mine at Lawyers is said to have produced 171,200oz of gold and 3.6Moz of silver between 1989-1992.
Benchmark is earning an initial 51% of Lawyers from PPM Phoenix Precious Metals and had spent $2.2 million by December of the required $5 million (US$3.7 million) spend on exploration by June 2021.
It can earn up to 75% by issuing shares and spending a further $4 million (US$3 million) on exploration in the same timeframe.
It expanded the project last month by 30% by staking new claims to take the land package to 127km2.
Benchmark last month said Sprott Asset Management had made the lead order in its flow-through share placement at 22c that raised $1.9 million (US$1.4 million) in the first and second tranches.
The company's shares are up 20.8% year-to-date, last trading at 29c to capitalise it at $14.7 million (US$11 million).