4251: Cueva en una Mina, La
Barrio de Arriba 30T 444736 4799566 (Datum: ETRS89. Accuracy code: G) Altitude 162m
Length 327m Depth 37m Vertical range 45m
Area position

Updated 4th January, 19th February, 9th, 31st May 2016; 20th September 2019

   Walk up the track past the main mine (Mina Favorita, site 1561) and instead of turning sharp right to the obvious barn go straight on up a newly cleared track to a wire gate. At this point a newly built cabin of white blocks can be seen. Go through the gate and take the upper track to an excavated platform above the cabin. The excavation has revealed what is now an obvious mine entrance.
    The light from a natural shaft can be seen from the entrance. Beyond the shaft is a blind adit. Halfway to the shaft a left turn takes you to a chamber which, to the right, also leads to the shaft. Ahead is a down-climb of some 3 metres to a natural 18m shaft (three 8mm bolts installed).
    At the bottom of the shaft a rubble heap formed from mine deads leads steeply to a chamber. Ahead is a calcite slope with extensive stalactites above which, with care, leads to a blind grotto. To the left is a step down into an inlet passage. Continue in the same direction across the inlet and up a mud slope. Follow the mud banks to the left and then drop steeply into the main passage. To your left can be seen the other side of the rubble heap. To your right, a passage of growing dimensions leads to a series of roomy chambers linked by stooping arches. The whole main passage has a flat floor of semi-dry cracked mud with a tiny rivulet meandering through it. There is extensive calcite in places. The final impressive chamber terminates in a small, chest-deep lake with no way on beyond. The continuation of the cave probably lies behind the extensive roof-high calcite on the right.
    The inlet passage near the entrance pitch gradually lowers to a flat-out crawl under delicate stalactites and becomes too tight after 26m but, 10m along the inlet, a squeeze to the left leads to a round 3m high chamber with no way on.
(Description: Phil Goodwin)

   Photos by the Grupo de Espeleología Pistruellos were published on-line in December 2015. Other references can be found on the Mina Favorita site although there is no indication on historic plans that this site was part of the Very Good Mine complex.
   The site was resurveyed in April 2016 to include more mined passage and the lake crossed in a small rubber dinghy to dig the mudbank. Hard and slow progress was made in clay/silt deposits. The strong draught in the system disappears in the lake area.

Reference: anon., 2015d (autumn logbook); anon., 2016b (Easter logbook); anon., 2018b (Easter logbook)
Entrance pictures : see GEP link below
Underground pictures : November 2015 : by the GEP (Google Photos) : Easter 2016 : from Carlos Lamoile Martinez
Video :
Detailed survey : plan pdf
Line Survey :
On area survey :
Survex file : April 2016