QUARTZITE

( Fr- quartzite; Ger- Quartzit/Quarzfels; Nor- kvartsitt; Rus- )

QUARTZITE

A. Quartzite. Native American arrow head (length ~ 3 cm) collected in Michigan. (© photo by D.L. Brittain)

B. Quartzite. "Greenlandite" cabochon (longer axis - 2.2 cm) from Godthåbsfjord area, southwestern Greenland. (© photo by Mark Cole, www.minershop.com)

C. Quartzite (dyed blue) paper weight (longest dimension - 5 cm). R.D. Titamgim collection. (© photo by Dick Dietrich)

D. Quartzite. Primitive quartzite disk money of West Africa -- see photograph, full caption and related text under REMARKS subheading.

DESCRIPTION: Quartzites consist of sand grains with intergranular silica (i.e., quartz) cement. Although the term quartzite is widely used as the name for metamorphosed sandstones, some geologists sometimes call silica-cemented sandstones either sedimentary quartzites or orthoquartzites, and distinguish them from metamorphosed sandstones by using the terms metamorphic quartzites or metaquartzites. Whatever, both have been used as gemrocks.
    Colors - white, smoky gray, rose-pink, yellowish, green, blue, mauve, nearly black -- with the color dependent upon the pigmentation material, which commonly is only discernible microscopically.
    H. 7
    S.G. ~ 2.7
    Light transmission - transparent to opaque
    Luster - waxy to vitreous
    Breakage - those with silica cement typically have imperfect to good conchoidal fracture; that described as imperfect typically exhibits granular surfaces; the fracture of most quartzites that do not exhibit conchoidal fracture is best described as irregular.

OTHER NAMES: Much quartzite occurs as the bedrock that "holds up" resistant ridges and hills. Distinct quartzite units are given stratigraphic unit names (see Appendix B, Glossary). -- Two examples are the Erwin Quartzite of the western Blue Ridge Province of eastern Tennessee, western North Carolina and southwestern Virginia; and the Flathead Quartzite of western Montana and adjoining Idaho and Wyoming.

Informal, nongeologic names have been used in the marketplace for some quartzites used as a gemrock. A few examples follow:

Aventurine (or aventurine quartz) - subtransparent to translucent quartzite that contains noteworthy amounts of one or more mineral pigments that give it a glittering sheen or spangled appearance, commonly of a single dominant color. Fairly common colors have been attributed widely to inclusions of the following minerals: red -hematite; reddish to yellowish brown - goethite; green - some green mica; blue or bluish purple - dumortierite.
Greenlandite (grønlandite per Johnson et al. (2000,p.74)) - a green to bluish green quartzite, the color of which is dependent upon the presence of fuchsite (a green, chromium-bearing mica) from the Nuuk (Godthåbsfjord) area of Greenland. On the basis of its having been dated as 3.8 billion years old, this quartzite has been marketed as “the world's oldest gemstone.” (see Fig. B)
Red jade - a misnomer given reddish quartzite.

USES: Perhaps the greatest use of quartzite as a gemrock is as a substitute for jade: "Indian jade," which is green, has been shown to be quartzite with fuchsite inclusions (Webster, 1949), rather than aventurine quartz, as frequently reported; dyed quartzite has been used as a simulate for both purple and pink jade.

Aventurine, especially green aventurine, has a long history of use as beads (both spheres and carved) and cabochons; blue aventurine has become a favorite of lapidaries more recently. Greenlandite has been fashioned into all sorts of things such as carved signet rings, bookends, and candle holders, and has been included in mosaics and intarsias.

Quartzite -- usually dyed to some pleasing color -- has been tumbled or otherwise fashioned into decorative items such as the illustrated paperweight (Figure C).

Other uses include statuary, including small busts etc.; carvings, including those for jewelry; and the widespread fashioning and marketing of replicas of so-called indian relics, especially arrow heads, that are used for all sorts of decorations both for adornment and display.

OCCURRENCES: A large percentage of the quartzites used as gemrocks occur in metamorphosed sedimentary rock sequences -- i.e., they are metamorphosed sandstones (metaquartzites). Many quartzites that have found use as gemstones are "local rocks" (in many cases, loose pebbles) that have caught the eye of someone who tumbles stones or perhaps even shapes them into, for example, cabochons. Three examples from Finnish Lapland are shown by Pulkkinen (2013 -- note three yellowish mounted cabs in lower right of Figure 3).

NOTEWORTHY LOCALITIES: Reddish - near Almeria, Sierra de Gador, Spain; green - Hassan District of the state of Mysore, India; “greenlandite” - Godthåbsfjord area, southwestern Greenland.

REMARKS: Several versions of etymology for the word quartz, the chief component of quartzites and the fundamental part of its designation, are recorded in the literature. In lieu of giving a summary of the versions in, for example, the Oxford English Dictionary, Webster's unabridged dictionaries and Mitchell (1979), it seems appropriate to repeat the following, given by good friend Clifford Frondel (1907-2002) in his classic "...Silica Minerals"(1962): "The name quartz, first used in the Middle Ages in Saxony for massive vein quartz, did not become an inclusive designation for the colored and fine-grained varieties of this mineral until about the end of the eighteenth century."

Some quartzites have been dyed or artificially stained -- e.g., dyed pink and "sold as pink jade" (Liddicoat, 1965-66, p.370). Also, see Figure C, which is just one of several colors, nearly all of which are quite obviously not natural, that articles fashioned from quartzite have been dyed before making them available in the marketplace. The quartzite of some of these items was apparently dyed before fashioning, but most appear to have been dyed after they were fashioned.

D. Quartzite. Primitive quartzite disk money of West Africa (diameter ~ 5 cm). See information in the following paragraph. (© photo

Pomexport Ltd., reproduced here by permission from www.NumberOneMoneyMan.com)

Quartzite formerly used as money in West Africa has become a desired collector's item. It is reported that "These quartz stones with conically drilled holes ( from both sides )were a popular high value money form in West Africa, particularly amongst the Asante ( in modern day Ghana ) from the 17th Century onward. Each piece measures approximately 2 inches ( 5 cm ) and weighs about 3 - 3.5 ounces ( 80 to 100 grams ). It was believed that these fell from heaven with magical powers and were sometimes ground into a consumable dust." (www.pomexport.com)

The following sculptures, though not examples of the use of quartzite as a gemrock -- i.e., their sizes are greater than the general limits ascribed to gemrock use in this document -- seem noteworthy here: “Statues carved from a ... brown-and-white swirled quartzite - such as the enormous head of Amenhotep III (circa 1390-1352 BC)[a grandfather of King Tut] - that looks as though it was smoothly poured from a soft serve ice cream machine.” (undated circular “Brooklyn Museum features an exhibit of ancient Egyptian art from the British Museum”).

SIMULANT:

***Snow quartz - white, "matte-finished tumbled pieces [of bubble-bearing silica glass] . . . produced by 'fusing quartz' and then rapidly cooling it" is described as a so-to-speak man-made quartzite by Johnson and Koivula (1999). - [Hardness of glass is only 5-5½ as compared to 7 for quartz, the main constituent of quartzite.]

REFERENCES: No general reference.

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