QUARTZITE (ID: 040) GEOLOGICAL CLASSIFICATION (Genetic classification) Introductory Quartzite is a metamorphic rock composed mainly of quartz (until 99 %) and definition (visu) sometime presents little crystals of mica. Usually, white to grey in colour, but impurities can cause quartzite to be pink, red, purple, yellow, orange, brown, green, or blue. Presents vitreous sheen and cannot be scraped with a pocket knife. Petrologist's Quartzite is a metamorphic rock that results of a compaction and definition recrystallization of quartz sandstone, composed mainly of quartz (until 99 %), and sometime presents little crystals of mica. Non-foliated (massives), granoblastic texture (the crystals form a mosaic of grains roughly equidimensional, with a strong tendency to hexagonal packing), fused quartz grains, medium to coarse grain size Commercial In the commercial stone industry, a “quartzite” will be called “stone”. definition (if any) GEOMECHANICAL CLASSIFICATION (Behavioural classification, Goodman, 1989) I. Crystalline D. Randomly oriented and distributed silicates minerals of uniform grain size. texture DESCRIPTION OF LOCAL SAMPLE Geological Fisgas de Ermelo quartzite (Nature park of Alvão, Northern of Portugal) is description of local transparent white to grey in colour, with golden mica crystals. Some faces sample present oxide stains. Other information The sample outcropping at formation of Armorican quartzite, pertaining to the about the outcrop Lanvirniano-arenigiano of the early Ordovician, composed of alternating quartzite, metasiltstone and phyllite with levels of intermixed iron, impure quartzite, grey-black phyllites and fine quartzite (ICNF: Património Natural (2004), p.5) Weathering grade of II sampling outcrop (ISRM, 1981) Location 41° 22′32.50″ N, 7° 51′ 47.00″ W ENGINEERING CLASSIFICATION OF INTACT ROCKS (General classification) ISRM classification R0 R1 R2 R3 R4 R5 R6 by strength. USC Extremely Very Weak Medium Strong Very Extremely (MPa) (ISRM, 1981) weak weak (5-25) strong (50-100) strong strong (0.25-1) (1-5) (25-50) (100-250) (>250) Deere and Miller classification by strength and deformation properties (Deere and Miller, 1966)

Mechanical General values Particular (local) properties values (if any) (unaltered) Young’s Modulus (E) (GPa) 36.5–88.3 (AASHTO, 2002) Poisson’s coefficient (ν) 0.03–0.22 (AASHTO, 2002) Uniaxial compression strength (MPa) 62–379 (AASHTO, 2002) P wave velocity 5000–6500 (González de Vallejo, 2002) mi (Hoek and Brown criterion, 1980) 20 ± 3 (Hoek, 2006) Basic friction angle (Φb) Not available Physical properties Dry unit weight (kN/m3) 26-27 (Goodman, (unaltered) 1989) Porosity 0.1–0.5 (González Vallejo et al, 2002) Engineering uses The interlocking crystalline structure of quartzite makes it a hard, tough, and others durable rock. Support plane foundation, dams support, building material, concrete aggregate, ballast, rip-rap, decorative features, etc. Difficult excavation References: • American Association of State Highway and Transportation Officials (2002) Standard Specifications for Highway Bridges. Washington, CD 20001 • González de Vallejo, L.I., Ferrer, M., Ortuño, L., Oteo, C., 2002. Ingeniería Geológica. Prentice Hall. MadridHoek E, Brown ET (1997) Practical estimates of rock mass strength. Int J Rock Mech Min Sci. doi: 10.1016/S1365- 1609(97)80069-X • Goodman, R.E., 1989. Introduction to Rock Mechanics, 2nd edition. John Wiley and Sons. New York • Hoek, 2006. Practical rock engineering. Available in https://www.rocscience.com/learning/hoeks-corner

Last modified: 13 February 2019