'Where do I begin, if you are interested in the spiritual aspects of each stone rather than the physical, emotional or psychological help theses stones can provide then this is the book for you.
Although to be fair Robert Simmons provides you with information that some other authors don't. Such as the structure, mineral habit and where they can be found. The book tells you which chakras are associated with each mineral, its key words and to which element it belongs. It takes you a while to go through the information to find what you need. I ended up starting with Naisha Ahsian's contribution and going from there.
Robert appears (and this is just my opinion) to have included only those stones in which he has an interest. So it isn't anywhere complete; for example, there is a general overview of Agate and then he goes on to describe some of the varieties in the family. On the other hand he goes into esoteric detail about Azeztulite as he contributed to the discovery of the spiritual healing properties of these stones, the fact that you can't buy most of them seems to be irrelevant to the author.
On the whole after weeding out the things that I needed from this book, I would recommend this book for the more unusual stones that have been included and for healers to add to their collection. I wouldn't recommend this book for beginners.