... If used for agriculture and horticulture, we suggest you use golden vermiculite, because its PH is 6.5-7.2, for ... 5-9.5, that's to say, compared with silver vermiculite, golden vermiculite is more neutral. In Japan, Korea market, our customers ... choose golden vermiculite used for agriculture and horticulture .2.Featuresfireproof,heat insulating,sound ...