If you're under the impression that natural insulation materials are the safest ones to use, it might be time to think again. Vermiculite is a natural insulation material — but it’s one that you definitely don’t want to have in your attic.
Vermiculite is a mineral mined from the earth, composed of shiny flakes that look like mica. When this mineral is put in an oven, it expands like popcorn. Expanded vermiculite is lightweight, fire-resistant, and odorless; since it has an R-valueMeasure of resistance to heat flow; the higher the R-value, the lower the heat loss. The inverse of U-factor.
of about R-2 per inch, it was used for decades as an insulation material.