Why is granite always used in homes?

Answer 1

Granite is extremely sturdy and resistant to damage and is also very common.

What make this a good question is that over the last century granite has become known to become mildly radioactive when it degrades - it emits radon, a carcinogenic substance. There are places that are statistically mildly more dangerous to live in as a result. Examples include Aberdeen in the north-east of Scotland (known as 'The Granite City" - where almost the entire city center was built from granite from a local mine, and it rains all the time - and the Island of Jersey in the English Channel (which is composed entirely of granite being washed by the sea). Both these places show very, very small statistical increases in cancer rates compared to nearby areas without such a granite presence.

To degrade granite takes a lot of constant energy and erosion though so if you have any in your house you are entirely safe.