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Isoclasite

Formula:
Ca
 
2
[OH|PO
 
4
] · 2H
 
2
O
System:MonoclinicColour:colourless, snow-white; ...
Hardness:1
Name:From the Greek for "equal fracture," in allusion to the cleavage.
This page provides mineralogical data about Isoclasite.

Classification of Isoclasite

IMA status:Questionable/Doubtful
Strunz 8th edition ID:7/D.36-30
Nickel-Strunz 10th (pending) edition ID:8.DN.10

8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
N : With only large cations
Dana 8th edition ID:42.6.2.1

42 : HYDRATED PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
6 : A2(XO4)Zq·xH2O
Hey's CIM Ref.:19.4.4

19 : Phosphates
4 : Phosphates of Ca
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Type Occurrence of Isoclasite

Type Locality:Jáchymov (St Joachimsthal), Ostrov, Krušné Hory Mts (Erzgebirge), Karlovy Vary Region, Bohemia (Böhmen; Boehmen), Czech Republic
General Appearance of Type Material:Transparent crystals, to 4 cm in length, partly altered to a milky colored material.
Year of Discovery:1870
Geological Setting of type material:Reddish dolomite vein in hornfels.
Associated Minerals at type locality:
DolomiteChalcedony

Physical Properties of Isoclasite

Lustre:Vitreous, Pearly
Diaphaneity (Transparency):Transparent
Comment:Lustre pearly on cleavages.
Colour:colourless, snow-white; colourless in transmitted light.
Hardness (Mohs):1
Cleavage:Distinct/Good
On {010}, distinct.
Density (measured):2.92 g/cm3

Crystallography of Isoclasite

Crystal System:Monoclinic
Morphology:Crystals minute, dull, prismatic [001]; also occurs as cotton-like fibers.

Optical Data of Isoclasite

Type:Biaxial (+)
RI values: nα = 1.565 nβ = 1.568 nγ = 1.580
2V:Calculated: 54°
Maximum Birefringence:δ = 0.015

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Low
Dispersion:r > v strong

Chemical Properties of Isoclasite

Formula:
Ca
 
2
[OH|PO
 
4
] · 2H
 
2
O
Essential elements:Ca, H, O, P
All elements listed in formula:Ca, H, O, P
Analyical Data:
CaO (49.51)
P2O5 (29.90)
H2O (20.59)
total (100.00)

Relationship of Isoclasite to other Species

Related Minerals - Nickel-Strunz Grouping):
8.DN.05Natrophosphate
Na
 
7
(PO
 
4
)
 
2
F·19H
 
2
O
8.DN.15Lermontovite
UPO
 
4
·OH·H
 
2
O
8.DN.20Vyacheslavite
UPO
 
4
(OH)·nH
 
2
O
Related Minerals - Hey's Index Grouping:
19.4.1Monetite
CaHPO
 
4
19.4.2Apatite-(CaOH)
Ca
 
5
[OH|(PO
 
4
)
 
3
]
19.4.3Brushite
CaHPO
 
4
·2H
 
2
O
19.4.5Buchwaldite
NaCaPO
 
4
19.4.6Canaphite
CaNa
 
2
[HPO
 
4
]
 
2
 · 3H
 
2
O
19.4.7Mundrabillaite
(NH
 
4
)
 
2
Ca(HPO
 
4
)
 
2
·H
 
2
O
19.4.8Whitlockite
Ca
 
9
Mg[PO
 
3
OH][PO
 
4
]
 
6
19.4.9Brianite
Na
 
2
CaMg[PO
 
4
]
 
2
19.4.10Petersite-(Y)
(Y,Ce,Nd)Cu
 
6
[(OH)
 
6
|(PO
 
4
)
 
3
] · 3H
 
2
O

Other Names for Isoclasite

German names:
IsoclasitIsoklas
Spanish names:
Isoclasita

Other Information

Other Information:Readily soluble in acids.
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 Isoclasite

Reference List:Sandberger, F., (1870): "Ueber Isoklas und Kollophan, zwei neue Phosphate": J. prakt Chemie, Neue Folge, 2,125-130 (as Isoklas).

Sandberger, F., (1870): Neues Jahrbuch für Mineralogie, Geologie und Paleontologie, Heidelberg, Stuttgart: 306 (as Isoklas).

Dana, E.S. (1892) System of Mineralogy, 6th. Edition, New York: 835.

Larsen, E. S. (1921): "The microscopic determination of the nonopaque minerals": US Geol. Surv. Bull. 679: 92.

Journal of the Czech Geological Survey (1997): 42(4): 24-25, 118-119.

Internet Links for Isoclasite

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    Localities for Isoclasite

    (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.
    Czech Republic
     
    • Bohemia (Böhmen; Boehmen)
      • Karlovy Vary Region
        • Krušné Hory Mts (Erzgebirge)
          • Ostrov
    		Sandberger, F., (1870), J. prakt. Chemie, Neue Folge, 2, 125-130; Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: 933.
    Portugal
     
    • Aveiro District
      • Albergaria-a-Velha
    Mineral and/or Locality
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