The Bright Star sand box was named Big Rock, and came in many different sizes. I found silica "sand" at a building supply yard for eight bucks for a hundred pound bag. Silica is a non-organic man made product similar to sand, used for sand blasting, etc., and comes in many different grades (size of the granules). I used Grade 60, which is granules of very small size. Their very small size allows more granules to fit in a cubic inch, thereby providing more absorption and dissipation of vibration. Anything higher in grade that 60 was almost a powder.
The "sandboxes" Bright Star made for placing on top of components (to damp chassis resonances and vibrations) were named Little Rock, also offered in various sizes. They actually were filled with some kind of granules (neither sand nor silica) that provided not only damping, but also magnetic shielding.