VOLCANIC STONE PLANTERS Natural volcanic stone (pumice) offers wonderful organic forms and porosity for a variety of plants, especially succulents. Lightweight but naturally strong, these planters will vary in shape and size depending on the original stones. 6″ W 3″ H (Approx.) Item no longer available. 8″ W 4″ H (Approx.) 10″ W 6″ H (Approx.) Item no longer available.