Expanded perlite is a kind of natural acidic glassy volcanic lava, a non-metallic mineral. Xinaynag Zhongzhou is the world's best quality perlite producer. Horticultural Perlite Agricultural Expanded Perlite: Horticulture perlite ore is expanded or popped by rapid, controlled heating, it expands up to 15 times its original volume and takes on a foam-like cellular appearance â?? essentially clusters of microscopic glass bubbles, creating a porous structure. This physical transformation makes expanded perlite an extremely effective aggregate for use in horticultural growing mixes â?? or, by itself, as a medium in hydroponic growing and as a rooting medium. Size: 3mm-6mm Usage: 1. Grow seeds and nodes 2. Produce seeding 3. Cultivation in greenhouses 4. Hydroponic Cultivation 5. Turf and landscaping 6. Growing media for indoor and outdoor gardening