Kyanite specimens from this border area between the towns of Montejo de la Sierra (Madrid) and El Cardoso de la Sierra (Guadalajara) have been the subject of discussion for a long time. In the area there are different deposits from which they can belong. In this specimen, the Baltasar Sánchez label is preserved, indicating the specimen from El Zahurdón, in Montejo de la Sierra. In the area we have toponyms such as Corrales de Zahurdón. Peter Seroka, to whom this piece belonged, indicates already in 1973 the presence of kyanite about 1000 m from the milestone of Km 3 of the road from Montejo to El Cardoso (Miguel Calvo's Mines and Minerals of Spain), see discussion in this link.
This specimen shows a group of kyanite crystals on a matrix with quartz, with an intense color. It is accompanied by the two mentioned labels. Very interesting...

Size: 6.7 x 4.5 x 2.2 cm.
Main crystal: 39 mm.

Col. Baltasar Sánchez; Col. Peter Seroka (#604).

Very well defined microcline crystal that shows us a very clean prism finished in complex shapes among which the Baveno twin can be observed. This specimen comes from the Peter Seroka collection and belongs from the quarries in the Bustarviejo area (Madrid).

Size: 7.8 x 2 x 2 cm.
Found in ±1990.

Col. Peter Seroka (#798).

This specimen may not stand out for its beauty but for us it stands out for its location and the origin of the specimen. It is a chalcedony with opal from the area near Vallecas, in Madrid. Fluorescent under SWUV. The sample belongs from the Bergakademie in Freiberg and due to the attached labels we can place it in the 19th century, when Vallecas was a small village. Through the other labels we can also follow its evolution in collections until a few decades ago. A piece with history, without a doubt.

Size: 5.7 x 4.5 x 2.3 cm.
Found in s. XIX.

Freiberg Bergakademie; Min. Geolog. Inst. Hamburg; Col. M. Ruppe; Col. G. Klimm
Classic locality