El Jabali mine represents a 15x15 m, steeply inclined excavation with two cross cuts and a 9 m vertical shaft to surface within limestone and quartz diorite
. Most of the mineralization at the El Jabali mine is in the form of veins, with one breccia identified.
The survey accurately identified all of the known mineralized quartz veins, as well as a minimum seventeen additional structures that are similar in geometry and appearance within the same quartz diorite
Three main geological units lie in the area of El Vapor district, (Fig 1): (i) San Lucas quartz-feldspathic gneisses (Gonzalez, 2001), which contains lenses of amphibolite and marble and are Proterozoic (Feininger et al., 1972); (ii) Segovia batholith of Jurassic age (160 [+ or -] 7 M.a., K/Ar in hornblende, Feininger et al., 1972), consists of a diorite with textural and compositional variations of quartz diorite
and locally hornblende gabbro; and finally, (iii) Segovia sedimentary rocks in the west of Segovia mainly composed of black shales interbedded with siltstones, sandstones and intraformational conglomerates, which in the north of the area have been dated between the upper Aptian and the lower Albian (Feininger et al., 1972) based on macro-fauna dating.
Intrusive ultramafic rocks and quartz diorite
displace these basement metamorphic rocks in some places.
The Echeng batholith comprises granite and minor quartz diorite
, while the Tieshan batholith consists of quartz diorite
and minor gabbro.
The Landry Brook pluton is divided into three units: gabbro to quartz diorite
, quartz monzodiorite to monzogranite, and monzogranite.
The Ruby Range Batholith is a large plutonic complex which underlies the south and central portion of the claim group, locally composed of quartz diorite
, tonalite and granodiorite with lesser amounts of diorite, gabbro and granite.
The lithology of intrusive rocks consists of gabbro, diorite, quartz diorite
, granodiorite, biotite granite and leucogranite.
At the Tonglushan deposit, a typical representative of this type, quartz diorite
porphyries have intruded gypsum-bearing limestones of the Triassic-age Daye Formation.
Material mined from the Fennell Pit is mainly hard rock in the form of quartz diorite
and andesite which requires conventional drilling and blasting.