Thanks for your question.
The base of the Arundel can get vey hot. This model is not suitable for a 12mm hearth so it can potentially reach temperatures of over 100 degrees Celsius.
The User manual, in the downloads section, gives this advice about hearths:
The fireplace to which the stove is installed must be made from durable fireproof materials.
Thin stone slabs (less than 50mm) risk cracking unless cut into sections to allow for expansion and backed by heat resistant concrete.
Even beyond the safety clearances stated items subjected to radiant heat from the stove can still become extremely hot, therefore please take care when siting items such as fuel, paper etc.
Hope this helps?