I’ve collected rocks (minerals) since I was very small. They would range in size from very tiny like small seeds to very large like bowling balls. But when I got older and began getting more serious about my collection, I began to notice that rock & mineral dealers would categorize their specimens by sizes.
The sizes included Cabinet, Miniature, and Thumbnail. I’ve also heard of Micromounts or Toenails. Some people have said there are no official sizes, and that dealers often use their own personal rules for size. Others suggest using the sizes that are specified for exhibitors at large mineral shows.
I’ve seen Cabinet size spoken of as being able to fit into a 5 inch cube, but I have also seen it listed as 2 to 4 inches with “Large Cabinet” as greater than 4 inches. Miniatures have been listed as being able to fit into a 2 inch cube or 1-1/8 inch to 2.5 inch. Thumbnails have been listed as being able to fit into a 1 inch cube or a 16th inch to 1-1/8 inch. And it is said that Micromounts should fit into a 1×1.5×1 inch cube.
I ran across a person who had many years experience in show competitions and had been involved in mineral judging. He mentioned that sometimes there is a size category called Toenail, which will fit into a 1.5 inch cube. This person listed formal definitions as follows: Thumbnail: Must fit into a 1″ cube Miniature: Must fin into a 2″ cube Small Cabinet: Must fit into a 5″ cube Cabinet: Too large to fit in a 5″ cube
My personal size preference usually ends up being Miniature to Small Cabinet. I prefer my minerals to be around the 2” to 4” size, but I do sometimes go for ones that are larger or smaller. I find that the 2 to 4 inch range gives a nice size that often does not need magnification and also doesn’t take up a large amount of space for my collection.
I have a nice wall cabinet where I display some of my favorites. The rest are stored in Plano Rack System storage cases. I love these sturdy cases with adjustable divided trays and large top cavities where I can put my larger specimens.