Rosin made from hash, or hash rosin, is considered by many to be one of the purest forms of cannabis concentrate. Cannabis rosin is made by combining high heat and immense pressure. Terpene and cannabinoid-rich oil (resin) is forced out of cannabis plant material called trichomes using a rosin press. Why U Gelly is a hybrid weed strain made from a genetic cross between Gelato and The Don Mega. This strain is 30% sativa and 70% indica.