rocks/stones

Hi

In the text that I read the author sometimes uses the word stone and sometimes "rocks". I'm not sure if he means the same by using these two words. I looked up in a dictionary and it said that in US, Can and Austr. rock = stone. The book was written by an American writer.

Here's the excerpt:

In these spells, use your powers of visualization and concentration to direct the energy through the stones. Here, the rocks are usually  focal points or tools that add little power of their own. Some of them are amulets and talismans of a kind. The stone pile, detailed below under "Cairn of Power," collects energies from the earth, but the rocks themselves aren't necessarily powerful.

So, do you think that here "rocks" and "stones" are one and the same thing?

Thank you

Thank you  Feebs!

Gemstones usually are regarded as semi-precious: amethyst, garnet, peridot, lapis lazuli, turquoise and so on, often used in fine jewellery.

In the context, rocks can be regarded as  those minerals which are not semi-precious, often containing crystalline interiors: agates, geodes, amazonite, quartzes and so on.