Resources of 38.3 million tonnes grading 41.3 grams per tonne silver include an indicated 12.3Mt at 45.5gpt silver and a measured 1.1Mt at 47.3gpt silver.
A mine plan and reserve estimate is expected in the current quarter.
The current production scenario involves treatment of about 500,000t stockpiles beginning in the third quarter followed by mining from two pits in February next year.
Wonawinta, located 85km south of Cobar, features an 850,000t per annum processing plant.
Shares in Manuka were up 2% to A46c in afternoon trade, capitalising the company at about $124 millon.
