Calcium Carbonate - CaCO3.
The most finely ground calcium carbonate flour available. Made from pure oyster shells. Small quantities used in grain spawn jars prevents sticking and clumping. Best when used in conjunction with Calcium Sulfate (Gypsum Powder - CaSO4). Not necessary for most species but required when growing Agaricus brunnescens
For agriculture and mycology uses only. Not for human consumption.
Qualifies for same shipping rate as seeds.