Is there a difference between rock and stone?
Ayers Rock is made out of sandstone. Before it was deemed protected, if you mined chunks out of Ayers Rock and exported them they would have been called "stone".
You might want to post the question of the English Language & Usage site & see what answers you get there. The definitions of rock & stone may be due to the words originating in different parts of England & over time the difference has been lost to the vast majority of English language speakers & users.
@Fred I just checked over at the site you had recommended. Apparently someone has asked this question back in 2010. See here:http://english.stackexchange.com/questions/5931/whats-the-difference-between-rock-and-stone I asked this question thinking there might be some quantifiable definition that distinguishes the two terms. From that site one answer was that, "Stone is of Germanic origin, rock is of Romance origin. That's the real difference. English has many synonyms due to words from different sources." -- GEdgar
I'm quoting from my old The Penguin Dictionary of Geology by D. G. A Whitten & J. R. V. Brooks, published in 1979.
Rock (1) To the geologist any mass of mineral matter, whether consolidated or not, which forms part of the Earth's crust ... (2) The civil engineer regards rock as something hard, consolidated, and/or load bearing, which, where necessary, has to be removed by blasting. This concept also accords with the popular idea of the meaning of the word.
Stone In geology the word 'stone' is admissible only in combinations such as limestone, sandstone, etc., or where it is used as the name for extracted material - building stone, stone road. It should not be used as a synonym for rock or pebble.