Hacquet is remembered for his scientific journeys throughout the Austrian Empire. He was a polymath, and performed research in the fields of geology, mineralogy, botany, chemistry, ethnography, petrology and karstology. He is recognized as the first scientist to perform extensive exploration of the Julian Alps. In 1777 he was the first to try to ascend to the top of Triglav (2864 m), the highest peak in Slovenia, and reached Mali Triglav (2725 m). In 1789 he published a description of the 1786 debris flow at the Slano Blato Landslide. He was the first after Carl Linnaeus to distinguish the mineral dolomite from the limestone and described it already in 1778, 13 years earlier than Déodat Gratet de Dolomieu, as the stinking stone (, ). He met with Dolomieu in Laibach in 1784.