We have several rock-hounds here - as evidenced by the boxes of rocks that haunt the dark recesses under beds and in closets, when they're not strewn all over the floor! Of course, our "good" rock collections don't suffer the same fate. These have been used countless times in our homeschool, especially in our study of Earth Science. Kept in the schoolroom, the children are free to use them to identify other rocks or just to peruse for sheer delight. I guess you can tell that I am rather fond of rocks myself. The combinations and varieties that God has embedded in the Earth are astounding and beautiful. We had to "dig" a little for the information to stock these, but it was totally worth the effort!