This rock collection contains specimens from the three great classes of rock: Igneous, Metamorphic and Sedimentary. Our best igneous specimens consist of various varieties of basaltic lavas and granites. One notable lava specimen was collected in 1987 from an important geological location in Ascension Island in the Atlantic Ocean. The granites were collected mostly from England (particularly Cornwall), Scotland, the Channel Islands, Germany and Italy. The metamorphic collection is the smallest in all three classes and shows varieties of slate, marble and schist. The majority of the sedimentary collection is made up of limestone, sandstones, ironstones and coals.
The small coal collection was collected throughout the 1920s and has specimens such as Bituminous coal from South Wales, Jet from Whitby in Yorkshire, Kimeridge clay from Dorset, Alum shale from Whitby in Yorkshire and Lignite from near Newton Abbot in Devon.
Some rocks and minerals are derived from noted geological dealers such as the celebrated German company of Dr A. Krantz (1809–1872) and F. Krantz (1859–1926) founded in 1833.
Dr August Krantz established his mineral dealership in 1833 in Freiberg, Germany. He had studied pharmacy but his fascination with the ore-deposits around Freiberg led to a lifelong interest in geology. In 1837 the Krantz company moved to Berlin and important links with the scientific community rapidly developed. Business flourished in many countries all over the world.
In 1850 the company moved its head office to Bonn and opened a geological speciality shop that still exists today. When August Krantz died in 1872 his company was world famous and had gained gold medal awards in world exhibitions. Upon August Krantz´s death, his son-in-law Theodore Hoffman took leadership of the company, and later August Krantz´s nephew Friedrich Krantz took over in 1891. The business remains under the management of the Krantz family today.