Black Fluorite And Black Fluorite sand are available and from what Seachem tells me they are both identical in nutritent/mineral composition. I would go with the Black Fluorite sand as it is likely better for planting some fine root stem plants like ludwiga, bacopa, rotala, not to mention carpeting pants like hairgrass, and dwarf baby tears.

If you are in the US, these are some of the best prices I have seen for the regular Fluorite Black and Black Sand.
Aquarium Plant Substrates at Big Al's Online