Gerard Troost (1776–1850), scientist, was a native of Holland who obtained medical and pharmaceutical training through apprenticeships at Leiden and Amsterdam. His wide-ranging interests included geology, and in 1807 Louis Bonaparte, king of Holland, appointed him to assemble a royal mineral collection. In preparation for that mission Troost studied crystallography with René Just Haüy and geology with Abraham Gottlob Werner, and he originally planned to join a scientific expedition to Java but instead settled in Philadelphia in 1810. He became the first president of the Academy of Natural Sciences of Philadelphia in 1812, and he was elected to the American Philosophical Society in 1816. Troost was also involved in an unsuccessful effort to establish an alum manufactory in Maryland. By 1821 he was teaching mineralogy at the Philadelphia Museum and chemistry at the Philadelphia College of Apothecaries (later the Philadelphia College of Pharmacy). In 1825 Troost joined Robert Owen, William Maclure, Thomas Say, and Charles Alexandre Lesueur in an attempt to establish a utopian society at New Harmony, Indiana. Two years later the society was struggling and Troost moved his family to Nashville, where until his death he served as a professor at the University of Nashville. He was also appointed the first state geologist for Tennessee, held the post for many years, and was responsible for the first geological map of the state. Although Troost published extensively during his lifetime, his final work on the fossil crinoids of Tennessee, which he had submitted to the Smithsonian Institution for publication just before his death, lingered for decades in the hands of the reviewer James Hall, who plagiarized some of his work. The research was not released under Troost’s name until 1909 (ANB description begins John A. Garraty and Mark C. Carnes, eds., American National Biography, 1999, 24 vols. description ends ; DAB description begins Allen Johnson and Dumas Malone, eds., Dictionary of American Biography, 1928–36, 20 vols. description ends ; DSB description begins Charles C. Gillispie, ed., Dictionary of Scientific Biography, 1970–80, 16 vols. description ends ; Leonidas C. Glenn, “Gerard Troost,” American Geologist 35 [1905]: 72–94; Joseph W. England, ed., The First Century of the Philadelphia College of Pharmacy, 1821–1921 [1922], 63–8, 397; APS description begins American Philosophical Society description ends , Minutes, 19 Jan. 1816 [MS in PPAmP]; Philadelphia Journal of the Medical and Physical Sciences 2 [1821]: 207; Public Acts passed at the stated session of the Nineteenth General Assembly of the State of Tennessee [1832], 43–4; Richmond Enquirer, 27 Aug. 1850; Elvira Wood, “A Critical Summary of Troost’s Unpublished Manuscript on the Crinoids of Tennessee,” Smithsonian Institution, United States National Museum, Bulletin 64 [1909]: v–150).