|Name(s) in local language(s):||Localidad tipo para el rutilo, Horcajuelo de la Sierra, Madrid, España|
|Location is approximate, estimate based on other nearby localities.|
|Latitude & Longitude (WGS84):||41° North , 3° West (est.)|
|Margin of Error:||~7km|
|Köppen climate type:||Csb : Warm-summer Mediterranean climate|
Metamorphic outcrop with rutile-bearing metamorphic segregation veins in mica schists. This locality consists of a set of many different locations such 'Dehesa de la Cabezada' (the classic outcrop), 'Cerro de las Cabezuelas' (or 'La Dehesilla'), 'El Lanchar', 'El Frontil', 'Las Losillas', 'Rodeo del Lomo' and of course the surroundings of 'Arroyo de las Cabrillas'.
Rutile was described as a mineral species by Werner in 1803, from specimens purportedly from "Cajuelo, Vuitrago, Burgos". It is clear that this was an error, and the actual locality for the specimens studied by Werner was Horcajuelo de la Sierra (Madrid), where their existence had already been known as a curiosity, although not scientifically described, since well before. Consequently, Horcajuelo de la Sierra (Madrid) is the real type locality for this mineral. (The cause of Werner's erroneous reference to Vuitrago (Buitrago) may have been the historical fact that Horcajuelo belonged to the Señorío de Buitrago, from the Duques del Infantado until the abolition of the residual feudal regime in 1830).
The rutile specimens that were found spread in the soil at 'Mata de la Cabezada Hill' (Horcajuelo de la Sierra) had attracted the attention of local people during ages. They were called 'acerillos' (small steel pieces). Early mineralogists in the XVIIIth century identified them as red schorls. Herrgen (1799) reproduced the analytical data that Klaproth had published before in 1797 about the rutile specimens at this outcrop, one of the first locations to be studied in the world; he indicated 'Mata de la Cabezada Hill' as the locality for these specimens, a hill 'a quarter league' (1.5 km) from the village. These locations supported old mines that were called 'Pozos de los Moros' (Wells of the Moors) by Herrgen contemporaries where silver was obtained according to him. Rutile is found in one of the hillsides, the same with the 'pozos'; it appears spread in the soil from the basis of the hill. Specimens can occasionally be found nowadays but it is really difficult after several centuries of collecting. Rutile appears always as loose crystals, usually as rounded pebbles, sometimes with some massive quartz matrix, but this is not a primary outcrop. Single prismatic crystals with heavily longitudinal striation up to '3 inches long x 1.5 inches wide' (Herrgen 1799). Herrgen (1799) described also their 'constant tendency to join', that is twinning, and he reported twinned groups up to four members.
Lévy (1837a) pointed out some rutile specimens (single crystals and twinned groups) from this locality in H. Heuland collection. Twins (geniculated and cyclic) are even more frequent than single crystals.
(Ancient references in Calvo 2009, op. cit. below)
Regions containing this locality
|Eurasian Plate||Tectonic Plate|
Select Mineral List TypeStandard Detailed Strunz Dana Chemical Elements
5 valid minerals. 1 (TL) - type locality of valid minerals.
Detailed Mineral List:
|ⓘ Rutile (TL)|
List of minerals arranged by Strunz 10th Edition classification
|Group 4 - Oxides and Hydroxides|
|Group 9 - Silicates|
|Unclassified Minerals, Rocks, etc.|
List of minerals arranged by Dana 8th Edition classification
|Group 4 - SIMPLE OXIDES|
|Group 51 - NESOSILICATES Insular SiO4 Groups Only|
|Insular SiO4 Groups Only with cations in  and > coordination|
|Group 52 - NESOSILICATES Insular SiO4 Groups and O,OH,F,H2O|
|Insular SiO4 Groups and O, OH, F, and H2O with cations in  and > coordination|
|Group 71 - PHYLLOSILICATES Sheets of Six-Membered Rings|
|Sheets of 6-membered rings with 2:1 layers|
|Group 75 - TECTOSILICATES Si Tetrahedral Frameworks|
|Si Tetrahedral Frameworks - SiO2 with  coordinated Si|
|Unclassified Minerals, Mixtures, etc.|
List of minerals for each chemical element
Sort byYear (asc) Year (desc) Author (A-Z) Author (Z-A)
Calderón, S. (1910) Los Minerales de España. Junta para Ampliación de Estudios e Investigaciones Científicas. Vol. 1, 416 pp., Vol. 2, 561 pp.
Calvo, M. (2009) Minerales y Minas de España. Vol. IV, Óxidos e Hidróxidos. Escuela Técnica Superior de Ingenieros de Minas de Madrid - Fundación Gómez Pardo. 752 pp.
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