A process includes reducing one or more pieces of cannabis plant matter to a powder by freeze-drying the one or more pieces of cannabis plant matter, and then extracting one or more chemicals from the powder by pressurizing the powder in a pressure vessel with along with liquid or supercritical carbon dioxide. The carbon dioxide dissolves the one or more chemicals. The powder is then depressurized to precipitate the one or more chemicals out of the carbon dioxide, and the precipitated chemicals can then be collected. For example, the freeze-drying ruptures the plant cells in the cannabis plant matter, thereby exposing or releasing the chemicals in the plant cells.