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Rutile type locality, Horcajuelo de la Sierra, Madrid, Spaini
Regional Level Types
Rutile type locality- not defined -
Horcajuelo de la SierraSierra
Madrid- not defined -

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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 PlateTectonic Plate
Iberian PeninsulaPeninsula

Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Mineral List

5 valid minerals. 1 (TL) - type locality of valid minerals.

Detailed Mineral List:

Formula: Fe2+3Al2(SiO4)3
Formula: KAl2(AlSi3O10)(OH)2
Formula: SiO2
Rutile (TL)
Formula: TiO2
Type Locality:
Formula: Al2(SiO4)O
Formula: A(D3)G6(T6O18)(BO3)3X3Z

List of minerals arranged by Strunz 10th Edition classification

Group 4 - Oxides and Hydroxides
Rutile (TL)4.DB.05TiO2
Group 9 - Silicates
Unclassified Minerals, Rocks, etc.

List of minerals arranged by Dana 8th Edition classification

Rutile (TL)
Group 51 - NESOSILICATES Insular SiO4 Groups Only
Insular SiO4 Groups Only with cations in [6] and >[6] coordination
Group 52 - NESOSILICATES Insular SiO4 Groups and O,OH,F,H2O
Insular SiO4 Groups and O, OH, F, and H2O with cations in [4] and >[4] 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 [4] coordinated Si
Unclassified Minerals, Mixtures, etc.

List of minerals for each chemical element

H MuscoviteKAl2(AlSi3O10)(OH)2
B TourmalineA(D3)G6(T6O18)(BO3)3X3Z
O RutileTiO2
O SillimaniteAl2(SiO4)O
O TourmalineA(D3)G6(T6O18)(BO3)3X3Z
O AlmandineFe32+Al2(SiO4)3
O QuartzSiO2
O MuscoviteKAl2(AlSi3O10)(OH)2
Al SillimaniteAl2(SiO4)O
Al AlmandineFe32+Al2(SiO4)3
Al MuscoviteKAl2(AlSi3O10)(OH)2
Si SillimaniteAl2(SiO4)O
Si AlmandineFe32+Al2(SiO4)3
Si QuartzSiO2
Si MuscoviteKAl2(AlSi3O10)(OH)2
K MuscoviteKAl2(AlSi3O10)(OH)2
Ti RutileTiO2
Fe AlmandineFe32+Al2(SiO4)3


Sort by

Year (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.

External Links

- http://www.foro-minerales.com/forum/viewtopic.php?p=119538 (discussion about the locality in Spanish language)

- http://www.foro-minerales.com/forum/viewtopic.php?t=5029 (detailed discussion about the erroneously reported rutile type locality 'Cajuelo/Horcajuelo' in Spanish language)

- http://www.igme.es/museo/publicaciones/Coleccion_Minerales_CAM2.pdf (Madrid minerals catalog of Geominero Museum, in Spanish language)

- http://www.igme.es/museo/publicaciones/cuadernos/Cuadernos%20del%20Museo%20Geominero_numero%2028_ingles.pdf
(Madrid minerals catalog of Geominero Museum, in English language)

ATTENTION: This is a locality revised by FMF Mineral Forum. We suggest do not make any changes or alterations to this locality file without discussing. Contributors could bring proposed updates to his attention either under the 'Mistakes and Errors Forum' in Mindat or directly in this thread http://www.foro-minerales.com/forum/viewtopic.php?p=119538#119538 in FMF Forum. Thank you.

ATENCIÓN: Ésta es una localidad que ha sido revisada por Foro FMF. Se ruega no introducir ningún tipo de modificación en esta ficha sin dialogarlo antes en la sección 'Mistakes and Errors Forum' de Mindat o directamente en este hilo http://www.foro-minerales.com/forum/viewtopic.php?p=119538#119538 de Foro FMF . Gracias.

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