I noticed some rocks for sale at our local Dollar Tree the other day and my curiosity got the best of me. They are simply marked as "River Rocks" and are black. I do not currently have a streak plate so I roughed up the surfaces with a diamond coated rotary bit. Powder colors range from gray and brownish-grey to white. They are harder then glass but softer then quarts. They are also attracted to a magnet, but weakly so (most can barely be picked up by a neodymium magnet). I checked a small piece for specific gravity and came up with 4.8. When broken they have a rough surface with very fine crystals (almost microscopic). Bellow is a picture of some of the rocks after cleaning (they came with some kind of wax coating). I'm afraid it is not the best quality. Any help would be appreciated.
