perlite
noun
per·lite ˈpər-ˌlīt 
: volcanic glass that has a concentric structure, appears as if composed of concretions, is usually grayish and sometimes spherulitic, and when heated expands to form a lightweight aggregate used especially in concrete and plaster and as a medium for potting plants
perlitic
ˌpər-ˈli-tik
adjective 
Example Sentences
Recent Examples on the Web For pots, use cactus soil with the addition of about 30% to 40% perlite to increase drainage, allowing water to drain through. 
Nicole Sours Larson, San Diego Union-Tribune, 22 Aug. 2022 According to Petal Republic, the best combination is a 2:2:1 blend of cactus potting mix, coarse sand and perlite or pumice. Alyssa Gautieri, Good Housekeeping, 5 Aug. 2022 This mix contains some peat moss along with perlite, worm castings, and lime. Brittany Vanderbill, Better Homes & Gardens, 6 May 2022 One local collector recommends a mix that is half seed starter mix, one-quarter coir chunks or chunky orchid bark, and a quarter small lava or pumice, or large perlite. Nan Sterman, San Diego Union-Tribune, 5 Mar. 2022 Inorganic amendments are perlite, pumice, vermiculite and Utelite. oregonlive, 2 Jan. 2022 The sundews should be grown in a medium of four parts fertilizer-free peat moss to one part perlite. New York Times, 26 Nov. 2021 Pumice or perlite — Quarried lava rock increases drainage and space for roots to grow. Claire Reid, Los Angeles Times, 10 Aug. 2021 They are made from Portland cement, perlite (or vermiculite) and water. Linda Gandee, cleveland, 6 Sep. 2021 See More
Nicole Sours Larson, San Diego Union-Tribune, 22 Aug. 2022 According to Petal Republic, the best combination is a 2:2:1 blend of cactus potting mix, coarse sand and perlite or pumice. Alyssa Gautieri, Good Housekeeping, 5 Aug. 2022 This mix contains some peat moss along with perlite, worm castings, and lime. Brittany Vanderbill, Better Homes & Gardens, 6 May 2022 One local collector recommends a mix that is half seed starter mix, one-quarter coir chunks or chunky orchid bark, and a quarter small lava or pumice, or large perlite. Nan Sterman, San Diego Union-Tribune, 5 Mar. 2022 Inorganic amendments are perlite, pumice, vermiculite and Utelite. oregonlive, 2 Jan. 2022 The sundews should be grown in a medium of four parts fertilizer-free peat moss to one part perlite. New York Times, 26 Nov. 2021 Pumice or perlite — Quarried lava rock increases drainage and space for roots to grow. Claire Reid, Los Angeles Times, 10 Aug. 2021 They are made from Portland cement, perlite (or vermiculite) and water. Linda Gandee, cleveland, 6 Sep. 2021 See More Word History
Etymology
French, from perle pearl
First Known Use
1833, in the meaning defined above