M917 - Perlite Specimen (Utah).

Today perlite has many uses including the construction industry, horticulture, as a filtration aid, in ceramics, foundries, insulation, and as a lightweight aggregate in mortar.

Perlite is not a trade name but a generic term for naturally occurring siliceous rock. The distinguishing feature which sets perlite apart from other volcanic glasses is that when heated to a suitable point in its softening range, it expands from four to twenty times its original volume.

From  Utah.

Price:   $ 2.15 each