Hanslune Wrote:
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> ... however
> concrete's ability to absorb and retain heat is
> different from limestone.

There's only one single thing you don't know so now your knowledge will be complete:

The single most important characteristic that determines solar radiation absorption is color. The single largest characteristic that determines temperature change is density. It is also density that is largely responsible for the rate at which an object will cool.

Since stone and cement are similar there should not be a substantial difference. That there is in actuality some unknown small difference will not explain why these stones are ice cold in the spring. It is apparently (obviously) the fact that they are cold in the spring that is preventing publication of the data.