What is the difference between a stone and a rock?

Answer 1

Rock is a naturally formed solid aggregate of one or more minerals. It is what stone is made from.

Stone normally is used to refer to rock which has been dressed, trimmed or otherwise engineered or used by man in construction of some sort, usually as discrete (individual) blocks. Also important is the fact that these blocks are no longer in-situ (i.e. they are no longer where they were formed and part of a larger cohesive rock mass) within the Earth. Examples are the use of "stone" as counter tops in kitchens or as ornamental cladding for buildings or the construction of columns and lintels in certain buildings. Another common use of large blocks of dressed stone is in sea defences and pier walls where the large dressed blocks forming the outer walls are known as armour stone.

Undressed but discrete blocks were also commonly used to construct dry stone walls in the UK to separate fields on farms. The importance here being their careful and deliberate placement, as opposed to "rock fill" which is also undressed discrete pieces of rock but which are end tipped with much less deliberation into piles or onto slopes (such as Rip-Rap which is a form of scour defence used in coastal sea defences and on embankment dams).

In common linguistic use a stone may refer to any small piece of rock that may or may not have been polished or weathered and that is lying on Earth's surface. For example the pebbles on a beach.