Helvite

helvite

[′hel‚vīt]
(mineralogy)
(Mn,Fe,Zn)4Be3(SiO4)3S A silicate mineral isomorphous with danalite and genthelvite. Also known as helvine.

Helvite

 

the group name for a mineral series with incomplete isomorphism, including helvite Mn4(BeSi04)3S, danalite Fe4(BeSi04)3S, and genthelvite Zn4(BeSi04)3S. The helvites are related to beryllium silicates, and they have a framework structure similar to the structure of the minerals of the soda-lite group. The composition of the intermediary minerals in the helvite group varies according to their Mn, Fe, and Zn content. The physical properties vary, and the color ranges from reddish brown (helvite) to yellow and colorless (genthelvite). The density of helvite is 3,200 kg/m3 and of genthelvite, 3,700 kg/m3; their hardness on the mineralogical scale is 6.0 to 6.5. Helvite crystallizes in the cubic system. It is found in the form of tetrahedric crystals, irregular granules, and impregnations in pegmatites, quartz veins, skarn deposits, and greisenized alkaline syenites and granites, enriched with sulfide minerals. In these forms it is found in Mount Francisco (western Australia), Iron Mountain (New Mexico), and elsewhere. Helvite is a valuable ore for the extraction of beryllium.

REFERENCE

Beus, A. A. Geokhimiia berilliia i geneticheskie tipy berillievykh mestorozhdenii. Moscow, 1960.

G. P. BARSANOV

References in periodicals archive ?
fr) had some interesting specimens of helvite dug in 2002 from a single pocket in a calcite-filled vein at the Tungsten Hill mine, Gage, Victoria Mountains, Luna County, New Mexico.
He showed me also some miniature-size, pale orange helvite crystals on quartz found for the first time at Madan, Bulgaria by the Spirifer group.
1008 Helvite, quartz and pink dolomite, Kapnik, Hungary, no.
Bryan Lees' sublease on the Cardwell claims resulted in the 2005 discovery of the finest helvite crystals known from the locality.
In July 1979, several years before specimens were generally available to the public, he organized a mining expedition to the Sawtooth Mountains in Idaho to dig for gem aquamarine crystals, crystallized topaz, helvite, spessartine, smoky quartz, and feldspar.
With the abundant specimens of spessartine, smoky quartz, orthoclase and combinations thereof which are dug at the two sublocalities called Yunling and Yunxiao (after villages near the productive outcrops), there occur rarely, Ottens writes, pseudo-octahedral crystals of yellow helvite resting on quartz or feldspar.
Helvite, apatite, topaz and molybdenite are of only rare occurrence but are found occasionally in collectible specimens.
At Tongbei, helvite and topaz occur, but no fluorite has been found to date.
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Luiz this time came up with some truly significant specimens of helvite and anatase/rutile from the fertile pegmatites of Minas Gerais--take the helvite first.
In the wholesale section, Luis Menezes had about 100 specimens, in thumbnail to cabinet sizes, of helvite from the Navegador mine, Conselheiro Pena, Minas Gerais, Brazil.
The exhibit also held rare franckeite, andorite, helvite and canfieldite specimens, all from South America.