Our 3/8"+ - 1/4+" pumice is ideal those wanting a clean hand screened pumice of a larger size for soil mix's. Our pumice is a natural volcanic product mined in the Southern Cascades Mountains of Oregon. You get only clean pumice... no rocks, roots or other debris. Known as the "rock that floats", pumice has many tiny gaps or air pockets. We ship our pumice by Priority Mail in boxes that are a little larger than the standard large flat rate square box. Our pumice is hand packed and bagged with a reusable tie for easy storage after you have used part of the bag. If your pumice dries before using, moisten it to keep dust from forming. Dust from any rock or potting soil product should not be inhaled and can be irritating for people with sensitive lungs. Our box contains 3 gallons dry measure, or will fill 6 -- #1 horticultural containers with pure pumice. Mix in 15%-20% pumice into a soil mix for general horticultural use including Japanese maples, raised beds and containers. For Giant Sequoia, Juniper, Sophora, Daphne, Monkey Puzzle trees, Franklin trees and other plants that need good drainage add 30% of pumice to mix. For cactus and succulents add 60 - 80% of pumice to 20 - 40% organic matter. For Bonsai soil mix use 33% pumice, 33% bark and 33% black lava or very course sand. Pumice can not be combined with other items for combined shipping. Ships UPS. Scenic Hill Farm is a licensed Oregon nursery -- license # L0170090NG.