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Junitoite

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Jun Ito
Formula:
CaZn2Si2O7 · H2O
System:
Orthorhombic
Colour:
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

Approved
9.BD.15

9 : SILICATES (Germanates)
B : Sorosilicates
D : Si2O7 groups, with additional anions; cations in tetrahedral [4] and greater coordination
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
14.7.17

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

General Appearance of First Recorded Material:
Randomly oriented colorless to lavender platy crystals up to 5 x 0.5 mm.
Year of Discovery:
1976
Geological Setting of First Recorded Material:
Contact metamorphosed zinc orebody
Associated Minerals at First Recorded Locality:

Physical Properties of Junitoite

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:
3.5 g/cm3 (Measured)    

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 Data:
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
Max Birefringence:
δ = 0.016
Image 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:
CaZn2Si2O7 · H2O
Essential elements:
All elements listed in formula:
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

9.BD.05BertranditeBe4(Si2O7)(OH)2
9.BD.10HemimorphiteZn4Si2O7(OH)2 · H2O
9.BD.20Axinite-(Fe)Ca2Fe2+Al2BSi4O15OH
9.BD.20Axinite-(Mg)Ca2MgAl2BSi4O15OH
9.BD.20Axinite-(Mn)Ca2Mn2+Al2BSi4O15(OH)
9.BD.20Tinzenite(Ca,Mn2+)2Mn2+Al2BSi4O15(OH)
9.BD.25VistepiteSnMn4B2Si4O16(OH)2
9.BD.30BoralsiliteAl16B6Si2O37
9.BD.35Werdingite(Mg,Fe)2Al14Si4B4O37
14.7.1SanborniteBa2(Si4O10)
14.7.2KrauskopfiteBaSi2O5 · 3H2O
14.7.3WalstromiteBaCa2(Si3O9)
14.7.4MacdonalditeBaCa4Si16O36(OH)2 · 10H2O
14.7.5EricssoniteBaMn22+Fe3+(Si2O7)O(OH)
14.7.6Ericssonite-2OBaMn22+Fe3+(Si2O7)O(OH)
14.7.7GillespiteBaFe2+[Si4O10]
14.7.8AndrémeyeriteBaFe22+(Si2O7)
14.7.9PellyiteBa2Ca(Fe,Mg)2Si6O17
14.7.10TaikaniteSr3BaMn22+(Si4O12)O2
14.7.11WillemiteZn2SiO4
14.7.12HemimorphiteZn4Si2O7(OH)2 · H2O
14.7.13ZincsiliteZn3(Si4O10)(OH)2 · 4H2O
14.7.14HardystoniteCa2Zn(Si2O7)
14.7.15PetedunniteCa(Zn,Mn2+,Mg,Fe2+)Si2O6
14.7.16ClinohedriteCaZn(SiO4) · H2O
14.7.18LarsenitePbZnSiO4
14.7.19EsperitePbCa2Zn3(SiO4)3
14.7.20HodgkinsoniteMn2+Zn2(SiO4)(OH)2
14.7.21GerstmanniteMnMgZn(SiO4)(OH)2
14.7.22GageiteMn21(Si4O12)2O3(OH)20
14.7.23FranklinfurnaceiteCa2Fe3+Mn32+Mn3+(Zn2Si2O10)(OH)8

Other Names for Junitoite

Name in Other Languages:

Other Information

Thermal Behaviour:
Strongly pyroelectric.
Health Risks:
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

Localities for Junitoite

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 for a valid mineral species. (FRL) indicates first recorded locality for everything else. ? 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.
Mineral and/or Locality  
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