Volcanic tuff (compact lapilli) was the most commonly quarried rock.
Yurena Naranjo-Mayor, Isabel Francisco-Ortega, Amelia Rodríguez-Rodríguez 2016, 'The quarry and workshop of Barranco Cardones (Gran Canaria, Canary Islands): Basaltquern production using stone tools', Journal of Lithic Studieshttp://journals.ed.ac.uk/lithicstudies/article/view/1779. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
Basal parts mainly consist of coarse-grained vitric tuffs that may contain some smaller pumice lapilli.
Stevo Dozet, Polona Kralj 2009, 'Volcanic succession of the Borovnik Member (Mohorje Formation), Bloke Plateau area,Central Slovenia', Geologijahttp://www.geologija-revija.si/dokument.aspx?id=1049. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
Lapilli-tuff and tuff seem to have higher matrix (grain) conductivitythan basalt.
Breiner, Niels, Waagstein, Regin, Balling, Niels 2006, 'Scientific results from the deepened Lopra-1 borehole, Faroe Islands: Thermal structureof the deep Lopra-1/1A borehole in the Faroe Islands', Geological Survey of Denmark and Greenland Bulletinhttp://www.geus.dk/publications/bull/nr9/nr9_p91-107.pdf. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
Low susceptibilities ranging from 0.4 to 4 are characteristic of altered basalts poorin magnetite, lapilli-tuffs and tuffs.
Waagstein, Regin, Abrahamsen, Niels 2006, 'Scientific results from the deepened Lopra-1 borehole, Faroe Islands: Magnetic logsfrom the Lopra-1/1A and Vestmanna-1 wells, Faroe Islands', Geological Survey of Denmark and Greenland Bulletinhttp://www.geus.dk/publications/bull/nr9/nr9_p41-49.pdf. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
The petrography of ignimbrites shows matrix-supported lapilli tuffs having a heterogeneous composition with insignificant lateral variations.
Alexandrina Fulop, Marinel Kovacs 2003, 'Petrology of Badenian ignimbrites, Gutai Mts. (Eastern Carpathians)', Studia Universitatis Babes-Bolyai: Geologiahttp://scholarcommons.usf.edu/geologia/vol48/iss1/art2/. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)