In the context of mining, estimation is an attempt to predict the value of one block or point which reach the closest value. An accurate geological modeling will be beneficial in mining activities in order to get the targeted of the company. This research focuses on natural resource estimation om massif limestone by applying kriging indicator and 3D Optsim methods in Sinar Asia Fortuna Company with geological model using Datamine application in the form of model block. This research categorizes limestone to 3 rocky types; masif limestone, vuggy limestone and chalk. As the result of the research, there are 75 % massif limestone, 23 % vuggy limestone and 2 % chalk. Meanwhile the proportion of limestone by applying 3D Optsim method is 52% massif limestone, 43 % vuggy limestone and 5 % chalk. Natural resource estimation on each rock type by applying kriging indicator method creates 130.889.422 ton massif limestone, 40.139.000 ton vuggy limestone and 3.490.000 ton chalk. These result are different from 3D Optsim method creates 90.750.00 ton massif limestone, 75.043.269 ton and 8.725.961 ton