insight on renewable/recyclable mineral fillers

While I can't answer all of your questions, I do see mineral fillers used in quite a few different LEED projects in order to increase the amount of recycled content. Building applications such as pavements, flooring, insulation, wall and even roofing materials use these fillers. I've read about some new products that use mineral fillers in paints and coatings as well.
For pavements, mineral fillers are often used in Portland cement mixes to add recycled content. Fly ash (residue generated in coal combustion in power plants) is a common filler in pavements, however other pozzolan (material that reacts with calcium hydroxide and water to form a cementitious compound) material can be used. In flooring systems I have seen linoleum products as well as rubber, cork, and various types of carpet use mineral filler in order to add recycled content to the product and be more “green.”
Armourcoat makes a gypsum plaster wall material called “Sculptural” which uses recycled mineral filler, while Thermafiber makes insulation products with a high content of recycled mineral filler. Roof materials using mineral filler often include roof board, shingles and coatings. Some paint products use recycled glass as the mineral filler.
So as you can see, there are numerous building applications where mineral filler can be used. Whether there is a trend in the use of mineral fillers is hard to say, but it does seem that there are many more products available now than there were a few years ago, which is a good thing.