You're thinking of promix. It's not just peat, it's also limed. I even think that adding a bit of extra perlite to promix is not a bad idea.

Greensand is a rich source of micronutirents, rather than an inert soil structure amendment like washed quartz sand is, although quartz may supply Si at low levels. I'm not sure what the solubility of Si04 is at pH 6.8.