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Roger Weller, geology instructor                                
Quartz Family Gemstones-by Audrey LaClair


Jasper is an impure variety of quartz that is opaque.  It is under the cryptocrystalline classification of quartz.  Jasper is usually red, brown, green, white or yellow in color.  It is made of silicon dixiode and is abundant in the Earth's crust.  It is found everywhere, especially in clay. Jasper does not hold much value and is used mostly for inexpensive jewelry.


photo by R.Weller


Jasper is "the stone for one of the 12 tribes of Israel, jasper was the legendary building stone of the Biblical walls"(Zeitner, p. 980).  Jasper is said to having calming effects on the human.  It is also to have said to cure insanity and snake bites, to help treat kidney and stomach disorders, to help the body remove toxins, and to help strengthen the bladder and liver.


photo by R.Weller


Apparently, there is some discrepancy about the differences of jasper, flint, chert, and sometimes agate.  One conclusion is "most geologists, and I have discussed this topic with many of them, distinguishing between jasper and chert in one way only.  That is by color.  If it is red cryptocrystalline quartz it is jasper.  If it is any other color it is chert" (Zeitner, p. 980).  "Gemologists and lapidaries are more likely to define jasper as an impure opaque chalcedony.  They are also less likely to assign a definite color to jasper.  In Gemcraft Quick and Leiper define jasper as an opaque form of colored chalcedony.  Parsons and Soukup point out that the main difference between agate and jasper is that jasper is opaque and agate is translucent” (Zeitner, p. 980).



photo by R.Weller




·        Jasper Chemical composition: SiO2

·        Class: tectosilicate

·        Crystal system: Hexagonal-R; 32 (trigonal-trapezohedral)

·        Crystal habit: massive microgranular quartz

·        Specific gravity: 2.58-2.91

·        Index of refraction: 1.54-1.55

·        Hardness: 6.5 to 7

·        Color: red, brown or yellow, colored by finely disseminated hematite or goethite

·        Luster: dull vitreous to greasy

·        Transparency: translucent to opaque

·        Cleavage: Cryptocrystalline quartz shows no cleavage, although parting may occur along laminations

·        Fracture: conchoidal

·        Streak: white


from (

Zeitner, June Culp.  “Jasper—Gem of Confusion.”  Lapidary journal  Dec. 1964: 980-998

V. 18, N.9