( Fr- vesuvianite; Ger- Vesuvian; Nor- vesuvian; Rus-  [i.e., idocrase] )

VESUVIANITE (Idocrase), (Ca,Na)19(Al,Mg,Fe)13(SiO4)10(Si2O7)4(OH,F,O)10.

A. Vesuvianite ("Californite") polished pieces -- turtle carving, diverse cabochons, and pendant (width - 2.5 cm) -- from "Pulga Jade" deposit near Pulga, Butte County, California.  Pendant  setting by Salvador Padilla, fashioning of stone by Chris Arp and Carey Robbins.  Kathy Saladin collection. (© photo by Roger Smith)

DESCRIPTION: Compact, massive varieties.
    Colors - most of the gemrock material that has has been fashioned and marketed is some shade of green;  some massive vesuvianite with a good potential for future use as a gemrock is of one or some combination of the following colors:  white, yellow, reddish brown, lilac or even bluish;  also, some of the massive green vesuvianite, widely referred to as californite, no matter where it was recovered, has streaks or irregular speckles of one or more of these other colors. 
- 7
    S.G. 3.28-3.55
    Light transmission - subtransparent to subtranslucent
    Luster -
dull to resinous to vitreous
    Breakage -  uneven or conchoidal
    Miscellany -
attacked by HCl.  Pakistani vesuvianite exhibits an orange fluorescence when exposed to x-rays;  most California vesuvianite does not fluoresce, and the rare specimens that do exhibit a green fluorescence (Crowningshield, 1965-66, p.366).  

OTHER NAMES:  Several names have been given to the mineral now recognized as vesuvianite by the CNMMN of the IMA. The designation idocrase, however, continues to be used widely, especially in gem(m)ology and the "lapidary world."  In addition -- and it is unclear whether most of the other names were meant to pertain to only  macrocrystalline vesuvianite, to compact massive varieties of vesuvianite, or to vesuvianite in general -- it seems only prudent to repeat the following names given this mineral as listed in Dana (1992) and/or Dana-Ford (1932): californite, colophonite, cyprine,  egeran,  genevite, loboite, wiluite (or viluite) and xanthite.  However, of these names, I have found only those listed below to have been applied to compact massive vesuvianite varieties used as gemrock rough.  (But, It also seems prudent to add that this is not to say that one or more of the other terms has not also been applied to the gemrock variety;  it merely indicates that I have not seen such use of those terms.)    

USES: Fine gemstones for jewelry as well as fine carvings of rocks made up largely of vesuvianite and grossular-vesuvianite, the latter usually called grossularite-idocrase, have been recorded (e.g., Crowningshield, 1967, p137).   Nonetheless, probably the most widely known use of compact massive vesuvianite is the substitution of the variety called Californite for jade.

OCCURRENCES: In metamorphic rocks, especially in skarns -- i.e., impure limestones that have undergone contact metamorphism. 

NOTEWORTHY LOCALITIES: Near Happy Jack mine, Siskiyou County and near Pulga, Butte County, California.

REMARKS: The mineral name vesuvianite, given by  Werner in 1795, was for its occurrence at  Mount Vesuvius, near Napoli (i.e., Naples), Campania, Italy, where it was found in metamorphosed limestone blocks that were engulfed within the lava.  The name idocrase, given by Haüy in 1796, was based on the Greek εἴδοϛ (forms) and  κρȃσιϛ (mixture);  this name was apparently chosen to direct attention to  the fact that the mineral has crystal forms that are common to other minerals --i.e., it is a mineral with so-to-speak mixed forms.  As already noted, vesuvianite, having priority is preferred in the mineralogical community, but idocrase persists in some literature, especially that of gem(m)ology, as well as rather widey in the marketplace.   The name californite was given to this material by the famous mineralogist and gemologist George Frederick Kunz, who was long associated with Tiffany and Company of New York City.

With all due regards to G.F. Kunz, I believe that gemrock vesuvianite would have gained more "prestige" in gemology if the term californite had never been introduced.  This is so, because It appears that its "new" name led to the additional attention given vesuvianite, and especially its comparison to jade and subsequent role as a jade simulant.  And, to me the use of any gem material as a simulant serves only to denigrate its use under its own name.  Massive vesuvianite is a great gemrock(!), and it seems to me that with little thought, its own name -- i.e. vesuvianite -- could have been used to advantage in the trade and in the marketplace:  The name vesuvianite was given by one of the most famous (or infamous, depending on ones views) early mineralogists;  he named it for one of the most widely known volcanoes in the world, Mount Vesuvius; and that volcano is near the famous city of Napoli (Naples).  Would this not have been a much better approach?  One can only guess.  In any case, it would have resulted in this fine gemrock's becoming recognized on its own merits, rather than as merely a good simulate for another gemrock (jade).

SIMULANTS:  I have seen no jewelry or ornaments mislabeled as vesuvianite or idocrase, and I have seen no records of such false labeling.   The designation californite, however, has been applied -- albeit rarely -- to an off-white grossular from Fresno County, California as well as to massive green vesuvianite.  Unfortunately, it is extremely difficult, if not virtually impossible, to distinguish between these two minerals in their massive forms without utilizing non-macroscopic means that utilize rather sophisticated equipment. 

REFERENCES: No general reference. Hemrich, 1964.

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Last update:  1 August 2005
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