Put the summary of the bug you're having here

What I expected to happen was...:
the sand and gravel should have fallen and their texture would have looked normal.

What actually happened was...:
The sand and/or gravel may either, disaper, change into a different looking texture, or turn black. When the sand/gravel hits the ground it turns normal

Steps to Reproduce:
1. place any block onto the ground or on the side of a structure
2. place sand or gravel on top
3. break the block below
Note: if this is preformed near a mob, the gravel or sand will look a bit like that mob's skin