3.5. Fischer assaySix oil shale samples were analysed by the Modified Fischer Assay method, using facilities at the CSIRO Division of Energy Technology. Approximately 30 g of each shale sample was heated in an aluminium retort to 550 °C at 12 °C/min, and held at that temperature for 40 min. The increase in mass of the condensate receiver was recorded, and the oil separated from the water by centrifuging. The oil yield was calculated in grams per 100 g of oil shale, and converted to litres per tonne of raw shale using density data for Sangkarawang oil shales from Ilyas (2000).