Grey ballast bulk product. It is color-matched to the ballast on trainboi1's WP procedural tracks and to my other Ballast 04 assets (groundtexture, spline, ballast piles). The appearance will vary on different rail-cars, depending on how the loads were UV mapped by the rail-car creators.
The texture was derived from the groundtexture, 412 Gravel, by Jordan412, with his permission. Note that replaceable commodity loads are currently not seasonal.