Hi all - this is my first post. I have two questions if anyone knows the answer or how to go about finding out. 1. Considering the design of an icebox or cooler, would sandstone (talc) be a better storage medium for coldness than ice? I did some research and found that the volumetric heat capacity of ice is 1.9 (in J/cm^3K) while sandstone is about 3. Also paraffin wax is about 2.3. Am I correct that the same size block of sandstone or paraffin wax would keep an icebox cold for longer? 2. My other question has to do with storing heat. If the heat capacity of sandstone is 3, and I heated a 20lb block of sandstone to 200 degrees Fahrenheit, how long would it take for it to cool to 70F? I have no idea how to model this question into a mathematical equation. Sorry if this is really basic.