The Nashville City Cemetery Association should be commended for their work in maintaining and cleaning up this cemetery (established 1822). I found it to be a clean and peaciful place that is the final resting place for a number of past residents of the city. The website is excellent and the records there helped me find Dr. Troost grave in section 29.1 near the cross section of Pine Avenue and Maple Avenue (inside the cemetery). The 1909 records show the grave at Section M-29, Lot 25 belonging to Mary Troost.
Panoramic images of part of the cemetery
The grave of Gerard Troost, M.D.; Ph. M. born March 15, 1776 (Bois-le-Duc, Holland) and died August 14, 1850 (Nashville, Tenneessee). He was a Professor of Chemistry and Geology at University of Nashville, 1828-1850. I think that university was merged into what is now Vanderbilt University.
Apparently, this grave marker is not the original and might be from 1905-1906. According to The American Geologist A Monthly Journal of Geology and Allied Sciences, Editor N.H. Winchell, Volume XXXV, January to June 1905. The article is in the February 1905 section entitled Gerard Troost by L.C. Glenn, Nashville, Tenn. pages 72-94.
To quote from the article on pages 89-90, "He sleeps in an unmarked and neglected grave in an obscure corner of the old city cemetery of Nashville. The State will be asked at the coming session of the legislature to place an appropriate marker over his grave and thus rescue from oblivion the last resting place of one who gave much of his time and skill to the service of the State in making known the existence or extent of natural resources whose later development has brought wealth and prosperity to their fortunate possessors. The portrait herewith reproduced is from a portrait in oil belonging to the Tennessee Historical Society."