Jervisit
| Jervisit | |
|---|---|
 |
|
| General and classification | |
| chemical formula | NaSc 3+ [Si 2 O 6 ] or (Na, Ca, Fe 2+ ) (Sc, Mg, Fe 2+ ) [Si 2 O 6 ] |
|
Mineral class (and possibly department) |
Silicates and Germanates |
|
System no. to Strunz and to Dana |
9.DA.25 ( 8th edition : VIII / F.01) 65.01.3c.06 |
| Crystallographic Data | |
| Crystal system | Monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Space group | C 2 / c (No. 15) |
| Lattice parameters |
a = 9.853 Å ; b = 9.042 Å; c = 5.312 Å β = 106.17 ° |
| Formula units | Z = 4 |
| Physical Properties | |
| Mohs hardness | 6th |
| Density (g / cm 3 ) | measured: 3.22; calculated: 3.272 to 3.31 |
| Cleavage | Perfect after {110} |
| colour | Light green |
| Line color | White |
| transparency | translucent to opaque |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.683 n β = 1.715 n γ = 1.724 |
| Birefringence | δ = 0.041 |
| Optical character | biaxial negative |
Jervisite is a very rare mineral belonging to the mineral class of silicates and germanates . It crystallizes in the monoclinic crystal system with the chemical composition NaSc 3+ [Si 2 O 6 ] and is therefore chemically a water-containing sodium - scandium- silicate. Structurally , Jervisit belongs to the chain and band silicates .
Jervisite forms small splinters less than a millimeter in size on elongated crystals.
With a Mohs hardness of 6, jervisite is one of the medium-hard minerals.
Etymology and history
The mineral was first described in 1982 by M. Mellini, S. Merlino, R. Renaldi, and P. Orlandi. They named the mineral jervisite after William P. Jervis. William P. Jervis was the curator of the Museo Industriale Italieno di Torino and the author of a book on Italian minerals.
In the first description, Mellini, Merlino, Renaldi and Orlandi described Jervisit with the chemical composition (Na 0.43 Ca 0.31 Fe 2+ 0.14 ) (Sc 0.66 Fe 2+ 0.15 Mg 0.19 ) Si 2 O 6 . They also stated that Jervisit is the natural analogue of NaScSi 2 O 6 .
To date, there are two ways of writing the chemical formula: The International Mineralogical Association (IMA) gives the formula NaSc 3+ Si 2 O 6 in its list of minerals , while the Handbook of Mineralogy of the Mineralogical Society of America gives (Na, Ca, Fe 2+ ) (Sc, Mg, Fe 2+ ) Si 2 O 6 .
In 2006 Merlino and Orlandi published a new publication in the Periodico di Mineralogia . In it they described other sites and corrected chemical and crystallographic data.
Jervisite is one of only around 14 known Sc minerals and with Davisite the second from the pyroxene group .
classification
Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the jervisite belonged to the mineral class of "silicates and germanates" and there to the department of " chain silicates and band silicates (inosilicates)", where it belongs to the large so-called pyroxene group . In this case, it belongs to the subgroup of clinopyroxene (system number VIII / F.01), along with Aegirin , augite , diopside , Esseneit , Hedenbergit , Jadeit , Johannsenite , kanoite , clino-enstatite , Klinoferrosilit , Kosmochlor , Namansilit , Natalyit , omphacite , Petedunnit , pigeonite and spodumene .
The 9th edition of the mineral classification according to Strunz , which has been valid since 2001 and is used by the International Mineralogical Association (IMA), also classifies Jervisit in the "chain and band silicates" department. This is, however, further subdivided according to the length and shape of the silicate chains, so that the mineral is classified according to its composition in the sub-section “Chain and band silicates with 2-periodic single chains Si2O6; Pyroxene family ”is to be found where it forms aegirine, jadeite, cosmochlor, namansilite and natalyite the Na-clinopyroxene or jadeite group.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Jervisit to the class of "silicates and Germanates" and there in the department of "chain silicate minerals". Here it is together with jadeite, aegirine, namansilite, cosmochlor and natalyite in the group of "C2 / c clinopyroxene (Na-clinopyroxene)" with the system number 65.01.03c within the subdivision "chain silicates: simple unbranched chains, W = 1 with chains P = 2 “to be found.
Crystal structure
Jervisite crystallizes monoclinically in the space group C 2 / c (space group no. 15) with the lattice parameters a = 9.853 Å ; b = 9.042 Å, c = 5.312 Å and β = 5.312 Å and 4 formula units per unit cell .
Education and Locations
Six sources are known from Jervisit.
The type locality and four other sites are in the province of Verbano-Cusio-Ossola in the north of Italy . In the vicinity of Baveno , Jervisit was found in Feriolo in the Ratti quarry and oltrefiume in the Locatelli quarry and in the Seula mine. At Omegna in Agrano , the mineral was found in both the Agrano granite quarry and the Giacomini quarry. The latter is the type locality.
The mineral is also found in Canada . There it was found in the province of Ontario in the Thunder Bay District near Walsh Township.
See also
literature
- Stefano Merlino, Paolo Orlandi: Jervisite, NaScSi2O6: a new occurrence, chemical data and crystal structure . In: PERIODICO di MINERALOGIA . tape 75 , 2006, pp. 189-194 ( PDF ).
Web links
- Webmineral - Jervisite (English)
Individual evidence
- ↑ a b c IMA / CNMNC List of Minerals; May 2015 (PDF 1.6 MB; p. 52).
- ↑ a b c d e f g Jervisite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy . Mineralogical Society of America, 2001 ( PDF ).
- ↑ a b c d e f g Mindat - Jervisite (English).
- ↑ a b Mineralienatlas: Jervisit
- ^ A b M. Mellini, S. Merlino, P. Orlandi, R. Renaldi: Cascandite and jervisite, two new scandium silicates from Baveno, Italy . In: American Mineralogist . tape 67 , 1982, pp. 599-603 ( PDF ).
- ↑ Webmineral - Mineral Species Containing Scandium .
- ↑ a b c List of localities for Jervisit in the Mineralienatlas and Mindat .