This bug report is regarding the inconsistent heat transfer of abyssalite to solids versus liquids.
The thermal conductivity for abyssalite is listed as '0.000'.
In sandbox mode, testing, 100kg of 272 Kelvin ice above 1000kg of 1500 Kelvin abyssalite, no visible heat transfer occurs.
If I change the ice to 100kg of 274 Kelvin water and unpause the game, the water instantly flash boils and the temperature of the abyssalite drops randomly by ~60+ Kelvin.
For bonus funtimes, note this 500C abyssalite with a layer of 1C crude oil above. Unpause, and the crude oil converts roughly 33% of its mass directly to petroleum, and the abyssalite drops to 400C.
Load the attached save, observe the temperatures of the test items, unpause, and watch what happens. Alternately, start a new game in sandbox mode. Create a floor of 1000kg blocks of abyssalite at 1500 kelvin. First, cover the abyssalite floor in 100kg blocks of ice and notice no visible temperature transfer occurring. Then, replace the ice with a lake of 100kg water above the abyssalite. Watch the water flash boil into steam and the temperature of the abyssalite drop sharply. Then, create a new floor of 1000kg blocks of abyssalite at 774 kelvin, cover it with 100kg tiles of crude oil at 0C, and watch the crazy bugged funtimes.