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Junitoite

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Formula:
CaZn
 
2
Si
 
2
O
 
7
· H
 
2
O
System:OrthorhombicColour:colorless
Hardness:
Name:
Named by Sidney Arthur Williams in 1976 in honor of Jun Ito [September 25, 1926 Japan - June 6, 1978 Chicago, IL], mineralogist and crystallographer, University of Chicago, Chicago, IL, USA.
This page provides mineralogical data about Junitoite.

Classification of Junitoite

IMA status:Approved
Strunz 8th edition ID:8/C.08-20
Nickel-Strunz 10th (pending) edition ID:9.BD.15

9 : SILICATES (Germanates)
B : Sorosilicates
D : Si2O7 groups, with additional anions; cations in tetrahedral [4] and greater coordination
Dana 8th edition ID:56.2.1.1

56 : SOROSILICATES Si2O7 Groups, With Additional O, OH, F and H2O
2 : Si2O7 Groups and O, OH, F, and H2O with cations in [4] and/or >[4] coordination
Hey's CIM Ref.:14.7.17

14 : Silicates not Containing Aluminum
7 : Silicates of Ba, Sr and Zn
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Type Occurrence of Junitoite

Type Locality:Christmas Mine (Red Bird shafts; Inspiration Mine; Hackberry shafts), Christmas, Christmas area, Banner District, Dripping Spring Mts, Gila Co., Arizona, USA
General Appearance of Type Material:Randomly oriented colorless to lavender platy crystals up to 5 x 0.5 mm.
Year of Discovery:1976
Geological Setting of type material:Contact metamorphosed zinc orebody
Associated Minerals at type locality:
XonotliteTyroliteSphaleriteSmectite GroupKinoite
CalciteApophyllite

Physical Properties of Junitoite

Lustre:Adamantine, Vitreous, Sub-Vitreous
Diaphaneity (Transparency):Transparent
Colour:colorless
Comment:sometimes milky white to pale lavender due to alteration
Streak:Colorless
Hardness (Mohs):
Tenacity:Very brittle
Cleavage:Very Good
{010} very good,{100} and {101} are poor.
Fracture:Micaceous
Comment:Breaks somewhat like mica in that the plates separate easily by breaking using a sharp point.
Density (measured):3.5 g/cm3

Crystallography of Junitoite

Crystal System:Orthorhombic
Class (H-M):mm2 - Pyramidal
Cell Parameters:a = 12.51Å, b = 6.31Å, c = 8.56Å
Ratio:a:b:c = 1.983 : 1 : 1.357
Unit Cell Volume:V 675.71 ų (Calculated from Unit Cell)
Z:4
Morphology:Crystals to 5mm with hemimorphic development. c {001}, b {010}, k {101}, p {111}, r {131}, -r {13-1}, -g {19-1}. (Viscinal forms may show herringbone pattern ["whishbone"])
Comment:Cell re-set from original
X-Ray Powder Diffraction:
d-spacingIntensity
6.25 (40)
4.70 (50)
3.53 (100)
2.82 (100)
2.54 (100)
2.52 (50)
2.35 (70)
1.540 (60)
Comments:ICDD 29-394

Optical Data of Junitoite

Type:Biaxial (+)
RI values: nα = 1.656 nβ = 1.664 nγ = 1.672
2V:Measured: 86° , Calculated: 88°
Birefringence:0.016
Maximum Birefringence:δ = 0.016

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Moderate
Dispersion:r < v
Pleochroism:Non-pleochroic

Chemical Properties of Junitoite

Formula:
CaZn
 
2
Si
 
2
O
 
7
· H
 
2
O
Simplified for copy/paste:CaZn2Si2O7·H2O
Essential elements:Ca, H, O, Si, Zn
All elements listed in formula:Ca, H, O, Si, Zn
Analytical Data:Easily soluble in dilute HCl [producing isoceles triangle etch pits on {010}] or rapid in HNO3. Decomposed by hot 40% KOH.
Looses water in closed tube and mass turns white. Easily fusible.

Relationship of Junitoite to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
9.BD.05Bertrandite
Be
 
4
(Si
 
2
O
 
7
)(OH)
 
2
9.BD.10Hemimorphite
Zn
 
4
Si
 
2
O
 
7
(OH)
 
2
· H
 
2
O
9.BD.20Axinite-(Fe)
Ca
 
2
Fe
2+
 
Al
 
2
BSi
 
4
O
 
15
OH
9.BD.20Axinite-(Mg)
Ca
 
2
MgAl
 
2
BSi
 
4
O
 
15
OH
9.BD.20Axinite-(Mn)
Ca
 
2
Mn
2+
 
Al
 
2
BSi
 
4
O
 
15
(OH)
9.BD.20Tinzenite
(CaMn
2+
 
)
 
2
Mn
2+
 
Al
 
2
BSi
 
4
O
 
15
(OH)
9.BD.25Vistepite
SnMn
 
4
B
 
2
Si
 
4
O
 
16
(OH)
 
2
9.BD.30Boralsilite
Al
 
16
B
 
6
Si
 
2
O
 
37
9.BD.35Werdingite
(Mg,Fe)
 
2
Al
 
14
Si
 
4
B
 
4
O
 
37
Related Minerals - Hey's Index Grouping:

- +
14.7.1Sanbornite
Ba
 
2
(Si
 
4
O
 
10
)
14.7.2Krauskopfite
BaSi
 
2
O
 
5
· 3H
 
2
O
14.7.3Walstromite
BaCa
 
2
(Si
 
3
O
 
9
)
14.7.4Macdonaldite
BaCa
 
4
Si
 
16
O
 
36
(OH)
 
2
· 10H
 
2
O
14.7.5Ericssonite
BaMn
2+
2
Fe
3+
 
(Si
 
2
O
 
7
)O(OH)
14.7.6Ericssonite-2O
BaMn
2+
2
Fe
3+
 
(Si
 
2
O
 
7
)O(OH)
14.7.7Gillespite
BaFe
2+
 
[Si
 
4
O
 
10
]
14.7.8Andrémeyerite
BaFe
2+
2
(Si
 
2
O
 
7
)
14.7.9Pellyite
Ba
 
2
Ca(Fe,Mg)
 
2
Si
 
6
O
 
17
14.7.10Taikanite
Sr
 
3
BaMn
2+
2
(Si
 
4
O
 
12
)O
 
2
14.7.11Willemite
Zn
 
2
SiO
 
4
14.7.12Hemimorphite
Zn
 
4
Si
 
2
O
 
7
(OH)
 
2
· H
 
2
O
14.7.13Zincsilite
Zn
 
3
(Si
 
4
O
 
10
)(OH)
 
2
· 4H
 
2
O
14.7.14Hardystonite
Ca
 
2
Zn(Si
 
2
O
 
7
)
14.7.15Petedunnite
Ca(Zn,Mn
2+
 
,Mg,Fe
2+
 
)Si
 
2
O
 
6
14.7.16Clinohedrite
CaZn(SiO
 
4
) · H
 
2
O
14.7.18Larsenite
PbZnSiO
 
4
14.7.19Esperite
PbCa
 
2
Zn
 
3
(SiO
 
4
)
 
3
14.7.20Hodgkinsonite
Mn
2+
 
Zn
 
2
(SiO
 
4
)(OH)
 
2
14.7.21Gerstmannite
MnMgZn(SiO
 
4
)(OH)
 
2
14.7.22Gageite
Mn
 
21
(Si
 
4
O
 
12
)
 
2
O
 
3
(OH)
 
20
14.7.23Franklinfurnaceite
Ca
 
2
Fe
3+
 
Mn
2+
3
Mn
3+
 
(Zn
 
2
Si
 
2
O
 
10
)(OH)
 
8

Other Names for Junitoite

Synonyms:
IMA1975-042
Other Languages:
German:Junitoit
Russian:Джунитоит
Spanish:Junitoita

Other Information

Fluorescence in UV light:Not fluorescent
Thermal Behaviour:Strongly pyroelectric.
Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Junitoite

Reference List:

- +
American Mineralogist (1976): 61: 1255-1258.

Mineralogical Magazine (1985): 49: 91.

Internet Links for Junitoite

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  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Junitoite details from Handbook of Mineralogy (PDF)
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  • Localities for Junitoite

    The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    USA
     
    • Arizona
      • Gila Co.
        • Dripping Spring Mts
          • Banner District
            • Christmas area
              • Christmas
    Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd. ed.: 231.
    Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd.ed.: 264; Williams, S.A. (1976), Junitoite, a new hydrated calcium zinc silicate from Christmas, AZ, Am.Min.: 61: 1255-1258.
    • New Jersey
      • Sussex Co.
        • Franklin Mining District
          • Franklin
    Dunn(1995):Pt3:414.
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