Re: What is the specific heat of granite? What are top five in heat capacity?

For the first part of your question, the specific heat of granite should 
be easy for you to find. Not only is it in "Perry's Chemical Engineers 
Handbook" (and probably many other standard handbooks) but a simple Web 
search on "specific heat" and granite turns up the number on a bunch of 
sites.

With regard to your "top five," that's not a meaningful question unless 
you narrow it a little. For one thing, the heat capacity of *any* fluid 
becomes infinite at its vapor-liquid critical point, so without any 
restrictions the top however many would be "any fluid at its critical 
point."

Another point to be appreciated is that "specific heat capacity" is on a 
per mass basis. Which is fine to talk about, but what has more physical 
meaning is the heat capacity per mole (or per molecule). As a first 
approximation, the heat capacity per molecule is proportional to the 
number of degrees of freedom (translational, vibrational, rotational) the 
molecule has. So, if you are looking for a high heat capacity per mass, 
you look for a relatively large number of degrees of freedom per unit 
mass.  If you are talking about substances at normal temperatures and 
pressures or in an ideal gas state (so you don't have to worry about the 
critical-point divergence) you get the highest specific heat capacity from 
things with the lowest molecular weights.  Like H2 (the highest as far as 
I know), or He, or Li, or LiH.  H2O is pretty high on the list, as is NH3 
which is a little higher than H2O. You can find tables for the elements 
and some other common compounds in the CRC Handbook of Chemistry and 
Physics (and probably other standard handbooks).

As for the part of your question that says "release that heat the 
slowest," there's no way to answer that without more specifics. That will 
depend on the thermal conductivity of the substance (for low thermal 
conductivity you want a lot of empty space, which is why vacuum flasks and 
styrofoam insulate well) but also on the conditions causing the heat 
transfer to take place. There's lots of ways for things to cool, and 
the "best insulating material" depends on what you are trying to do. In 
many cases, the "best insulating material" would be a total vacuum.