Fig. 2
Geologic and petrographical profile of the borehole Gn-1 with the samples investigated. 1 Soil with weathered detritus of the bedrock; 2 dark-grey, blackish-grey fresh slate; 3 grey, brownish-grey altered and fractured slate; 4 yellowish-grey, light-grey, strongly altered slate; 5 very strongly altered and fractured slate; 6 very strongly altered and fractured slate with blocks of relatively fresh slate; 7 dark-grey, silicified slate with several cm large white quartzite lenses, the latter showing evidence of corrosion; 8 whitish-grey, white smectitic clay (alteration product of slate) with quartzitic lenses that contain sulfide minerals (mainly, pyrite)