Non-water soluble cannabinoid acids are isolated from trichomes and flower of Cannabis genus by leaching with alkaline water. The leaching with alkaline water converts the cannabinoid acids to water soluble salts. The resulting solution of cannabinoid salts may be used as a source of acidic cannabinoids for pharmaceutical applications or the cannabinoid acid salts may be converted back to their acid form and precipitated into a high purity microcrystalline powder by acidification of the aqueous solution. Compounds that are not water soluble and do not form salts in alkaline water such as many pesticides, fungicides and off flavors will not be concentrated.