What is the current volume of natural asphalt?

Based on preliminary investigation including by applying geo-electric sounding, the asphalt deposit in just one area of north Buton is estimated 120,000,000 tons grading 10-30% impregnated bitumen by assuming specific gravity of 0.8. Locally, as heavy viscous asphalt of about 60% bitumen. The bitumen is impregnated in globigerina bearing limestone and marl. Explain the nature of Asbuton in terms of its: Composition of crude asphalt: Bitumen: 13 - 53 % Mineral Content: 28 - 30 % Refined asphalt: Bitumen: 52 - 55 % Mineral Content: 35 - 39 % Discuss the history of Asbuton. The early exploration of the asbuton deposits was carried out by mining engineers and geologists of the Nederlands Indies Geological Survey in the early 1920's to 1930's, with publication of preliminary results in the mid 1920's to late 1930's. The earliest reports were composed by Van Haeften (1924) and Zwierzycki (1925). Bothe (1928) reported on the some deposits areas, which because of their location were ...  more