A new linear model is presented herein to optimize strategic production scheduling of an open pit mine with multiple processing streams while accounting for investment decisions under mineral supply uncertainty. The solution approach consists of first solving the linear relaxation using an extension of the Bienstock-Zuckerberg algorithm to the stochastic optimization. Then, a rounding heuristic based on the topological sorting is applied, followed by a parallel multi-neighborhood Tabu search. The proposed method is applied to a multi-product open pit mine deposit, with the possibility of investing in new shovels, trucks or crushers to increase related capacities. Numerical experiments show that the proposed method manages to solve the instance within an optimality gap less than 1.5% in reasonable time. Results also display an increased expected net present value of 6% compared to the formulation without investment options.