The Museum’s petrological collection consists of a variety of rock specimens (more than 16,000 registered items) from different sources, a collection of thin sections (over 4,000 preparations) for the purpose of studying the rocks under a polarising microscope, and a collection of 33 large stone blocks on display outside the Martorell Museum (formerly the Geology Museum). The rock collection also contains a sub-collection of approximately 250 samples of sands. The collection dates back to the earliest days of the Museum (late 19th century) and has continued to grow thanks to the fieldwork done by the Petrology Department and to the donations from institutions and external museum staff. Collection fund Sources of acquisitions Preparation and preservation The petrology collection includes representations of most known types of rocks and a good selection of plutonic and volcanic rocks, in the different acid and basic varieties; metamorphic rocks (of differing degrees of metamorphism) and sedimentary rocks (carbonates, siliciclastics, evaporites, coals, bauxites, and so on). The collections cover an ample geographical sector that encompasses Catalonia (Pyrenees, Central Depression, Prelittoral Range, etc.), the whole of Spain, Europe and specific parts of America, Africa and Australia, where expeditions were sent in the 1960s to collect basic and ultrabasic rocks from the Precambrian shields. Antiga Collection This collection was acquired on 30 April 1988 from Pere Antiga i Sunyer, and consisted of 100 rocks. Today, 37 of them remain (all of similar dimensions) along with 13 thin sections from the collection. The provenance of the material is very well documented. Most of the samples are from France, but there are also some from Germany and the Czech Republic. As far as geological origin is concerned, most of the rocks are igneous. Large Blocks Collection The Large Blocks collection was begun in 1905 by Norbert Font i Sagué (1873–1910). It consisted of 133 large blocks of rock which were installed in Ciutadella Park, outside the Martorell Museum. The specimens were from the largest quarries in Catalonia. The collection was destroyed in 1929, but the Geology Museum conserved a small sample of each specimen. During the 1940s, the collection was reconstructed with 32 blocks, thanks to the intervention of a number of Catalan naturalists. In 2003 the Department of Architecture, Town Planning Sector of Barcelona City Council, undertook the restoration of the collection and the renewal of the explanatory labels. The collection currently on display consists of 33 blocks of large-sized rocks set against the main façade of the Martorell Museum, as well as several prismatic basalt columns positioned at the sides of the exterior hall, just as they were originally. Mining Collection This collection came from the exhibition opened in 1904 on Minería y Trabajos hidráulicos de Cataluña e Islas Baleares, con un anexo de carácter internacional para máquinas y material aplicable a las industrias Minera, Metalúrgica, Hidráulica y Eléctrica (Mining and Hydraulic Works in Catalonia and the Balearic Isles, with an international annexe for machines and material applicable in the mining, metallurgy, hydraulics and electrical industries). It was organised by Fomento del Trabajo Nacional (National Employment Development Association) to publicise the mineral wealth of Catalonia and the Balearic Isles. The material was accessioned into the Museum in 1905 (Gómez-Alba, 2001). The petrology collection has inventoried 32 specimens, all of which are in Spain. It comprises 22 sedimentary rocks and 10 igneous rocks. Rosals Collection In 1917 the Museum accessioned a collection of molluscs, geology and palaeontology donated by Joan Rosals i Corretjer. The petrology collection currently conserves 101 rock specimens from that collection. The samples are predominantly from Catalonia and the rest of Spain. There are also specimens, mostly igneous rocks, from Germany and France. The Catalan samples are mostly of porphyries, marlstones and hornblendes. Vidal Collection Within the sizeable geology and palaeontology collection donated by Lluís Marià Vidal i Carreras to the Board of Natural Sciences, deposited with the Martorell Museum in 1922, we have inventoried 235 specimens. All the samples are from Catalonia, mostly from Lerida and Gerona. There is a notable presence of samples from the Vall d’Aran and from the two Pallars regions. In lithology terms they are predominantly organic rocks (53 specimens), granites, marbles and fillites. RACAB Collection Since 1925 the Museum has been the repository of part of the RACAB (Barcelona Royal Academy of Sciences and Arts) collection. The petrology collection, with 1,143 inventoried items, contains specimens from all over the world. As is to be expected, for reasons of proximity the samples are predominantly European (approximately 900 items) and, more specifically, from Spain (524 items). Within Spain, the samples from Catalonia make up almost half of the items. This collection was created by some illustrious specimen hunters such as Jaume Almera i Comas (rocks mostly from France), Artur Bofill i Poch (metamorphic rocks from Barcelona), Ramón de Bolòs i Saderra (volcanic rocks), Eduard Fontserè i Riba (various rocks from all over Spain), Carles de Gimbernat (mostly volcanic rocks and rocks from Italy), Antoni Llobet i Vall-Llosera (rocks from Europe, especially France and Spain, and from America and Africa) and Joan Artur Maliban i Autet (volcanic rocks from the Canary Islands). From the lithology standpoint, the most notable items are the rocks of volcanic origin (343 specimens) like the large collection of rocks from La Garrotxa, and the collection of lava medals that Carles de Gimbernat had struck from the lava of Mount Vesuvius. The coal collection, with 142 specimens, is also quite considerable. Thin Section Collection To complement the documentation and research the thin section collection is created along with that of the rocks. This collection, with 4,197 samples, can be divided into two: that of the early thin sections, dating from approximately 1900 to 1950, and that of the new thin sections, from 1950 onwards. It encompasses many collections and benefactors, and the provenance and lithology of the preparations is very diverse. Standout donations are that of Gonzalo Moragas, which is the largest with 1,300 preparations, and that of Norbert Font i Sagué, which is the most unusual. From 1998 to 2004, when the Museum’s Thin Section Laboratory was operational, the collection was enriched with many new preparations. The three main sources of acquisitions which expand the Museum’s petrology collection day by day are: Contributions from curators, either through field samples collected for research projects or specimen harvesting for the purpose of filling in the geological and geographical gaps in the collection. Donations from institutions and people outside the Museum. Any donation must include a minimum of information for it to be accepted by the Museum. The donation of a petrology collection usually also includes a mineralogy collection. Many prominent members of the community, such as Jaume Almera, Marià Faura, Pius Font, Gonzalo Moragas, Joan Rosals, Baltasar Serradell and Lluís Marià Vidal, have made donations to the Museum. The collection also contains samples used in doctoral theses, end-of-course projects or research projects. All this well-documented material, with associated publications, is accessible for consultation and will be conserved in the appropriate conditions. Although in general the petrology collection requires no special conservation, we have initiated a process of adaptation which consists of the appropriate cleaning and conditioning of the samples and protection of the associated information. This will ensure the material is better conserved and will facilitate its consultation. Worth a special mention here are the saline rocks which, in some cases, will require a protective coating and to be kept isolated from humidity in special containers or cabinets. To ensure accurate classification of the samples, thin sections of the rock, about 30 microns thick, are taken for studying under a polarising microscope. One of the future projects of this department is to reactivate the thin section preparation laboratory, in conjunction with the palaeontology department.