It's hard to tell how large the pieces are without having anything next to them for scale... Can you take a picture of some of it in your hand? It looks like coarse sand to me, and the pieces that look like shells look like crushed beach shells like the ones you'd find in beach sand. There are lots of different types of shells and not all of them are good for the purpose of providing calcium to chickens. Oyster shell is the one usually used, as opposed to just any shell, because it's very crumbly and dissolves/digests easily, so the calcium is more easily available to the chicken's body. In fact it crumbles so easily that there's often dust at the bottom of the bag where the pieces rubbed against each other. Also, the oyster shell sold for chickens is usually white. And the granite sold as grit is fairly uniform in color. The particles in your picture come in different colors, which makes me think it's a collection of different materials, and neither grit (rock) sold for digestion, nor shell sold for calcium, would have this kind of varied look. This looks like it's a third product, but unfortunately I can't tell what... It really looks like coarse beach sand to me, and that won't meet either need of the chickens (may even be bad for them if it is indeed sand and hasn't been washed to remove the sea salt from it).Here is a picture of the sample. Take a look![]()