Here's the 600 (actually 552) sparkles per 20m square.
This time, I applied a reset transform to the entirety of all attached faces. This is a single mesh over the single snow field mesh. It seems to load just as slow, but jerks less in game than 200 individual meshes. Again, the sparkly is not spectacular when spread over such a large area, but it is starting to approach reality. Imagine using this glitter method to coat a few crystal faces in your caves!
Just a note: the underlying snow texture has been toned down by giving it an approximately half-saturation reducer. This is done by simply changing the diffuse and ambient values in the model file to 150/256, rather than 256/256 (1). I used the default texture settings in gmax to accomplish this. Nor sure why they picked 150, but it doesn't matter. The point is, the highest color your display can show is white. So white sparkles on stark white illuminated snow will be invisible. So you need a snow that is not stark white. Alter as desired.
One might also play with the underlying envmap image, as they did in vanilla placeables for the crystals and gold. Nothing says you have to use the wavy silver scale image for your snow. Planar snow may come in various colors, or you may wish your snow to reflect the sky of your world, not silver white.
Glow in the dark snow is also not out of the question. Try adding self illumination to force your colors, and make sparkles available at night.
Also note the black pixels in the picture above are also the same frost faces, but with the darker portion of the envmap showing. I've found that increasing the number of faces per square meter actually makes more black spots than it makes light spots. I assume this is a drawback of using the base metal envmap image. Perhaps a rounded envmap would be more realistic than a wavy one in this case. If you really want some serious sparkle, make a high luminance, and very granular, envmap, like salt or sand.
OTR's package of alternative envmaps has a few I liked: vdu_envmap028, 32, 69, and 8. Especially 8! If you have the package, examine how index 69 has more white than the rest. This causes the flicker to never go off, just cycle through high luminance values. Index 8 does a great job of cycling through whites with a mix of sky colors. It also has enough near-gray colors to turn of the flicker as you walk away.