The increased estimate is a function of drilling late in 2020 and being able to beneficiate the ore to achieve a 60% increase in head grade, allowing the cut-off grade to be dropped from 1750ppm to 1000ppm lithium.
McDermitt has now eclipsed Lithium Americas' Thacker Pass deposit containing 8.3Mt LCE (at a 2000ppm lithium cut-off grade).
The 1.43 billion tonnes at 1320ppm lithium deposit remains open with an exploration target range between 1.3 to 2.3 billion tonnes at 1100 to 1500ppm lithium.
Further drilling is proposed for the September quarter.
Jindalee raised A$9 million last month when it issued new shares priced at $1.50 each.
Shares in Jindalee were up 41.3% to $2.60 in morning trade, capitalising the company at $133 million.