No. As you can see from these images, rhino horn has a tubular structure. Individual tubules are roughly 50 to 300 microns in diameter and live horns have a natural moisture content of roughly 20%. These images come from a comprehensive independent study on the internal structure of rhino horns performed by the University of Ohio in 2006, and repeated again in 2011. The information contained in these studies formed the basis for our horn devaluation work. The entire 2006 research article can be read by clicking on this link:

2006_Hieronymus-Witmer-Ridgely_rhino_horn