JASPER

( Fr- jaspe; Ger- Jaspis; Nor- jaspis; Rus )

JASPER (See also CHALCEDONY and CHERT entries.)
 

A. Jasper toad, top, (height - 7.5 cm) by Gerd Dreher. Betty Llewellyn Collection. (© photo by Jeffrey A. Scovil)

B & C. Orbicular Jasper, center  Left: slab (field of view, width - 13.8 cm).  Gilbert Gauthier collection.   Right: cabochons (heights - up to 5.3 cm).  Don Olson & Associates.  This jasper, from Madagascar, is widely marketed as "Ocean jasper." The diversity of patterns exhibited by these cabochons provides examples of the virtually innumerable possibilities lapidaries have when fashioning pieces from this rock. (© photos by Jeffrey A. Scovil)

D. Jasper, bottom. Morrisonite (width - 7.6 cm). Don Olson & Associates. (© photo by Jeffrey A. Scovil)


DESCRIPTION: Dense microcrystalline quartz -- some people describe jasper as similar to chert whereas others compare it to chalcedony; my observations favor the correlation with chert because virtually all of the rock I have seen that has been called or labeled jasper is opaque or subtranslucent in thin splinters and has a dull to pearly luster like chert, which is quite different from the typical translucency and subvitreous luster of most chalcedony.  Nonetheless distinguishing certain specimens as one versus the others of these rocks is subjective and based on the experiences of the person naming them.
    Colors - typically red of diverse hues or brown; less commonly green or just about any color, white, gray or black;  even less commonly zoned -- e.g., ill-defined stripes that are yellow, bluish, purplish, gray or nearly black -- with some specimens cloudy, variegated, roughly banded and/or spotted.  In practice, color leads to some of the problems that arise when one is naming some materials  jasper rather than chert:  a "rule of thumb"  (albeit based on one's subjective sense of and feelings about color) to which I subscribe, is "if the given rock exhibits attractive colors call it jasper, otherwise call it chert."
    H. ~ 7
    S.G.
2.5-2.9
    Light transmission
- typically opaque (cf. agate)
    Luster - dull to pearly
    Breakage - subconchoidal fracture.

OTHER NAMES:  Nomenclature for diverse jaspers is not well established. -- The chief differences relate to the fact that some definitions are primarily descriptive whereas others are genetically or economically based.  In any case, anyone interested in collecting jasper should ever remain aware of the fact that jasper is treated in vast literature of economic geology.

As one might suspect for a gemrock of such widespread occurrence, jasper has been given many names. Adjectives and monomial terms applied have been based on such things as color and arrangement of colors, localities of occurrence, names of persons who were connected with the material, names thought to appeal to potential purchasers of items made from jasper, etc., etc.  Several of these names have been recorded by Hart (1927);  Dake, Fleener, and Wilson (1938);  GIA (1974);  and Mitchell (1985).  Some examples follow:

USES: Jasper has found widespread use in jewelry and for fashioning ornaments since its early use as beads and for seals.  Black jasper was used for intagli in Roman times (King, 1965, p.123);  most "Indian beggar beads" consist at least in part of diversely colored jasper;  many carvings are made of jasper; diverse jaspers have been used to make buttons... 

OCCURRENCES:  Much jasper appears to represent replaced limestone or dolostone -- in some places, extensive beds of those rocks.  It also occurs as a veins and nodules and otherwise configured components, commonly as part of the gangue of mineral deposits that appear to have formed as the result of hydrothermal or metasomatic processes.

NOTEWORTHY LOCALITIES:  See the localities noted with the terms listed under the OTHER NAMES subheading.  As might be suspected from going through that list, jasper is relatively common -- Merrill's catalog entries (1922, p.25-26) for nine specimens in the  U.S. National Museum collections include the following localities: Egypt (Nile River), England (Hertfordshire), India, Saxony, Siberia, and "Locality not recorded."  And, that list is fairly exemplary of the rather non-definitive locality labels I have seen on numerous specimens of jasper in several museums and private collections. In addition, it is common to see one locality listed for several diverse samples -- e.g., I suspect that labels reading simply San Bernardino California, indicate only that the specimens came from somewhere within the general area along Route 40 between Ladle and Newberry Springs, California.

Special attention is directed to Frondel's (1962) treatment of jasper -- in the Silica Minerals volume of the seventh edition of Dana's "System ..." -- where several localities for diversely colored jasper are recorded. Also, Evseev (1994, p.48) gives the following entry -- repeated here because of the relative difficulty in obtaining a copy of the publication in which it occurs:

"Jasper -- Since the 18th century, the Altai has been famous for decorative jasper varieties, which are used in large items -- Revnevskoye deposit (near the town of Zmeinogorsk) -- grey-green banded jasper (a large chunk of the Revnev jasper was used to manufacture a unique 3 x 5 m vase and columns in the Hermatage ... headwater of the Charysh River -- white jasper with black dendrites; Korgon River (confluent of the Charysh River) -- beautiful grey-violet porphyry; Transbaikalia -- 'Egyptian jasper' Ir-Nimi deposit (Far East) -- 'watercolor' jasper whose peculiar coloring is formed by bright blue patches on the red, dark grey, and brown background; specimens from this deposit came to be known quite recently in the 1970-1980s."

REMARKS: Jasper is recorded in ancient manuscripts (e.g., Exodus  XXVII:20).  Its etymology, as given in several references, is approximately the following:  Middle English (jaspre);  from Latin (iaspis);  Greek (ιασπιϛ - iaspis);  Persian (yašhm);  Arabic (yašb);  Hebrew (yāšhpêh);  Assyrian/Akkadian (ašhpū).    

The color and opacity of jasper is dependent upon its being so-to-speak "chuck full" of microscopic and submicroscopic inclusions, commonly of hematite and other iron-bearing minerals.

A velvety black variety of jasper, called Lydian stone or basanite, was formerly used as a touchstone -- i.e., a stone whose smooth surface when scratched with, for example, gold or silver or certain alloys, exhibits streaks that can be compared to streaks of known metals or alloys, and thus provide a means of identification, including even measurements of such things as the material's gold content. 

Red jasper and yellow jasper are thought by some scholars to have occupied positions one and ten, respectively, in Aaron's breastplate (see GLOSSARY);  other scholars have suggested that jasper occupied either the fifth or sixth position.    In addition,  the term given  the twelfth stone of the Breast plate of the High Priest, Yashpheh, has sometimes been translated as green jasper.

Jasper is indicated to constitute the first foundation of  walls of the Heavenly City (Revelation, XXI:19).

SIMULANTS:

Bloodstone - this chalcedony gemrock  [see CHALCEDONY entry] is sometimes called blood jasper.  In my opinion, this reported nomenclature seems outlandish -- considering their market values, it seems much more likely that jasper resembling bloodstone would be marketed as a bloodstone simulant. However, I must admit that some bloodstone looks more like jasper than like chalcedony. -  [In any case, fracture surfaces of chalcedony tend to be shinier than fracture surfaces of jasper.].

***Glass - Marilyn Jobe of Ellenton, Florida has fashioned beads from glass that closely resembles brecciated jasper - [inferior hardness].

***Iris jasper - an Iimori glass - [vitreous luster; inferior hardness].

***Jasperware (jasper ware) - Wedgwood china that resembles jasper, which has been molded into, for example, cameo-appearing pieces used in pendants, brooches, and earrings. - [Appearance suffices.].

***Porcelain jasper - "Hard, naturally baked, impure clay or porcellanite, which, because of its red color, resembles jasper" (Mitchell, 1985) - [Although appearance may suffice,  non-macroscopic means are often required.].

Sioux Falls jasper - brown quartzite used as a gemrock; from vicinity of Sioux Falls, South Dakota. - [vitreous luster].

In an opposite sense, the name Oriental jasper has been applied to bloodstone. - [As noted under the DESCRIPTION subheading, distinguishing some chalcedony from jasper, and even from some chert, is commonly subjective.]. 

REFERENCES: Blair, 1982; Dake, Fleener and Wilson, 1938; Frondel, 1962; Lovering, 1972.

| Top | Home |


R. V. Dietrich © 2014
Last update:  11 May 2013
web page created by Emmett Mason