Samuel James Shand, geologist, was the son of James Shand and his wife Catherine G. Hunter. He received his schooling at George Watson's College, Edinburgh, and continued his studies at the University College, Dundee (which later became Queen's College, University of St Andrews), where he obtained the degree Bachelor of Science (BSc) in 1905. While in Dundee he acquired his skills in silicate analysis and became interested in igneous petrology. He then went to Munster, Germany, to specialise in geology and was awarded a PhD in 1906 for his studies on a group of alkaline rocks from Loch Borolan in the Assynt district of the Scottish highlands. Returning to Scotland he was appointed assistant curator at the Royal Scottish Museum in Edinburgh, with responsibility for the geological collections. In 1910 he was awarded a DSc degree by the University of St Andrews.
In August 1911 Shand became professor of geology and mineralogy at Victoria College, Stellenbosch (which became the University of Stellenbosch in 1918). He held this position for 25 years during which he developed the new Department of Geology and profoundly influenced education in and the study of geology in South Africa. On the basis of his two doctoral degrees the University of the Cape of Good Hope admitted him to its DSc degree in 1911. During World War 1 (1914-1918) he served as a lieutenant in the Royal Engineers and assisted in finding water resources for the army in the Middle East. At the close of the war he worked briefly on the petrography of the reservoir limestones of the Iranian oil field. After returning to Stellenbosch he became increasingly interested in the alkaline rock formations of the Transvaal, especially at the Pilanesberg and at Phalaborwa, on which he published several authoritative papers over the years. During the Fifteenth International Geological Congress held in Pretoria in 1929 he led an excursion to Pilanesberg.
Some of Shand's earlier publications dealt with topics in general geology, geomorphology, structural geology, and palaeontology, mainly of the Western Cape, and in 1914 he presented fossils from the Bokkeveld group and a collection of rocks to the McGregor Museum in Kimberley. However, he gradually became an expert on the classification, composition and origins of igneous rocks. He was an excellent descriptive petrographer, had an intense love of rocks and minerals, particularly of the alkaline rocks and the minerals of which they are composed, was acutely aware of the importance of the chemical analyses of rocks and minerals, had a remarkable ability to organise and systematise, and may be regarded as the 'father' of South African petrology. His classification of eruptive rocks was based mainly on the extent to which the rocks were saturated with silica, their mineralogical composition and texture. The classification was later developed further in his book Eruptive rocks; their genesis, composition, classification, and their relation to ore deposits (London, 1927; 4th ed. 1951), which ensured his international reputation. According to Scholtz (1946) his classification of eruptive rocks and studies of the petrology of South African alkaline rocks constitute one of the most fundamental contributions made by members of the Geological Society of South Africa during its first 50 years. About 30 of his publications dealt with southern Africa, including 'The alkaline rocks of South West Africa' (Geological Magazine, 1915), 'The problem of the alkaline rocks' (Proceedings of the Geological Society of South Africa, 1922), The study of rocks (London, 1931, 3rd ed. 1951), and Earth lore: Geology without jargon (London, 1933). As indicated by the latter title, aimed at non-scientists, he was an advocate of simple terminology in one's own language. In addition to the work outlined above he discovered and first described pseudotachylyte (a cohesive glassy or very fine-grained fault rock that is composed of an extremely fine-grained or glassy matrix) and reported its occurrence at Parys in the Free State in 1917. The mineral shandite, a lead-nickel-sulfide occurring in serpentine, was named in his honour.
In July 1937 Shand resigned his position to accept an appointment as professor of petrology at Columbia University, New York, where he felt much disturbed by the effects of World War II (1939-1945) and by the death of his wife in 1947. He remained at Columbia until his retirement in 1950 when he returned to Scotland. There he was attached to the University of St Andrews and wrote his last important book, Rocks for chemists; an introduction to petrology for chemists and students of chemistry (London, 1952).
Shand was a Fellow of the Geological Society of London and was awarded its Lyell Medal in 1950. He was also a Fellow of the Mineralogical Society of London and the Royal Society of Edinburgh, and a member of the Geological Societies of America and South Africa. He became a member of the latter in 1912, served on its council from 1914 to 1916 and again from 1919 to 1938, was president in 1921, and was awarded its Draper Memorial Medal in 1937. In 1912 he became a member of the South African Association for the Advancement of Science and in due course contributed several papers to its annual congresses.
In January 1913 he married Joanna Margaret Jameson, but they had no children. He was a modest man with a fine sense of humour, a logical mind, and was widely read.