Our 1/8" - 1/64" pumice is ideal for seed starting mixes, or cutting propagation. Add 15%-30% to a peat/perlite based mix. Contains some fines. 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. Our pumice is hand packed and bagged with a reusable tie for easy storage after you have used part of the bag. Our box contains 5 quarts liquid measure. 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. We are a commercial Wholesale / Retail Plant Nursery with over 17 years mixing specialty potting mixes. Check out our other listings of custom potting mixes to select the perfect mix for your plants. Pumice can not be combined with other items for combined shipping. Scenic Hill Farm is a licensed Oregon nursery -- license # L0170090NG.