Fricken unpredictable as hell yields from my quartz-based thermite composition using aluminium. Might give magnesium a try next. Managed to get a few small, but nice looking chunks, fused into rounded pebbles/shot in the intense heat of the reduction. But only managed to get a few little pieces of raw silicon out of just under an oz of silica/micronized aluminium thermite. Perhaps its vaporizing the silicon as its formed. Getting mostly slag. Trying treating it with potassium/sodium tartrate in order to form an alum out of the Al slag, and dissolving any aluminium metal with caustic, but if I got any yield at all with my second charge its small. Too early to tell yet but it looks ugly as, compared to the nice shiny bright pieces of Si that I smelted out the last time.
The charge burnt just fine, flared fast and thoroughly, consuming the entire charge rather than being difficult to ignite like the first, the one I got the good bits of silicon from.