Johann Friedrich Ludwig Hausmann, German mineralogist and geologist, studied at the University of Goettingen, Germany, where he was awarded the degree Doctor of Philosophy (Dr Phil) in 1808. In 1801, at the age of 19, he published three papers on insect pests such as plant lice and the Spanish fly. However, his main interest was in crystallography. In 1803, at the age of 21, he wrote Kristallogische Beitraege, in which he introduced the use of spherical trigonometry in crystallographic calculations - the contribution for which he is particularly remembered. Yet his interest in insects remained and in 1807 he contributed a substantial paper, "Beitraege zur Insektenfaune des Vorgebirges der Guten Hoffnung" (Contribution to the insect fauna of the Cape of Good Hope) to the Magazine fuer Insektenkunde (Vol. 6, pp. 229-267).
After occupying various positions in the administration of mines from 1803 to 1806 Hausmann went on a journey of exploration in Norway and Sweden during 1806-1807. His experiences were written up in the form of a five volume work, Reise durch skandinavien (1811-1818), which made him a pioneer in the geological investigation of these countries. At this time he also recognised the north to south movement of erratic boulders by former glaciers in northern Germany. Meanwhile he had been appointed inspector of mines, foundries and saltworks in the Kingdom of Westphalia in 1809 and was stationed in Kassel. Two years later he was appointed lecturer (later professor) in mineralogy and technology at the University of Goettingen, where he remained for the rest of his career. He went on geological excursions in Germany, Austria and Switzerland, visited Italy in 1818-1819 and other western European countries in 1828-1829. Some of his research dealt with the stratigraphy and structural geology of western Europe, while in 1813 he published a three volume Handbuch der mineralogie.
Hausmann was the co-author of an article by F. von Stromeyer on crocidolite (blue asbestos) from the Northern Cape, published in Germany in 1831. As a friend of Reverend C.H. Friedrich Hesse* he visited the Cape in the 1830s, travelling as far north as Clanwilliam. He did some fossil collecting himself, but also received fossils from the surveyor W.F. Hertzog*, which the latter had collected along the Bushman's and Sundays Rivers from the Uitenhage Group and later beds, as well as in the rocks of the Table Mountain Group near Clanwilliam. Hausman wrote up his obsevations in a paper, "Beitraege zur Kunde der geognostischen Constitution von Sued-Afrika", which was published in the Goettinger gelehrter Anzeiger in September 1837. This paper provided the first description of the rocks of the Uitenhage Group, and he concluded that the fossils found there showed these rocks to be of Lower Cretaceous age - an early example of dating South African geological formations by their fossils. The South African fossils furthermore appeared to support the idea that living organisms in different parts of the world were more diverse during later (Cretaceous) times than during the period when earlier rocks, such as those of the Table Mountain Group, were laid down.
During his lifetime Hausmann published over a hundred papers, most in German, but some in French, Latin, Dutch, English and Spanish. Most dealt with mineralogy and crystallography, others with the geology of mountain ranges. Towards the end of his career he wrote Beitraege zur metallurgischen Kristallkunde (2 vols, 1850-1852). The mineral hausmannite, consisting of manganese oxides, was named after him.