Ghiaraite
A valid IMA mineral species
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Maria Rosaria Ghiara (b. 1948)
Formula:
CaCl2 · 4H2O
Specific Gravity:
1.838 (Calculated)
Crystal System:
Triclinic
Name:
In honor of Maria Rosaria Ghiara (b. 1948) who is Head of Real Museo Mineralogico of Napoli and Centro Musei delle Scienze Naturali e Fisiche dell’Università degli Studi di Napoli Federico II. Several years ago Ghiara began a program to promote scientific collaborations to obtain new information about the stored minerals from the Vesuvius volcano in the last 200 years.
Known synthetic compound. The type sample was collected at the Vesuvius volcano, stored in a sealed glass vial and deposited at the Real Museo di Napoli in 1872 by Arcangelo Scacchi. The combination of small grain size plus sensitivity to the moisture did not allow a better physical or optical characterization.
Unique Identifiers
Mindat ID:
43592
Long-form identifier:
mindat:1:1:43592:9
IMA Classification of Ghiaraite
Classification of Ghiaraite
3.BB.40
3 : HALIDES
B : Simple halides, with H2O
B : M:X = 1:2
3 : HALIDES
B : Simple halides, with H2O
B : M:X = 1:2
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Ghi | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Ghiaraite
Density:
1.838 g/cm3 (Calculated)
Optical Data of Ghiaraite
Type:
Biaxial (-)
RI values:
nα = 1.530 nβ = 1.557 nγ = 1.567
Max. Birefringence:
δ = 0.037
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Moderate
Comments:
From synthetic material
Chemistry of Ghiaraite
Mindat Formula:
CaCl2 · 4H2O
Element Weights:
Elements listed:
Crystallography of Ghiaraite
Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Space Group:
P1
Cell Parameters:
a = 6.3660 Å, b = 6.5914 Å, c = 8.5568 Å
α = 93.504°, β = 97.778°, γ = 110.557°
α = 93.504°, β = 97.778°, γ = 110.557°
Ratio:
a:b:c = 0.966 : 1 : 1.298
Unit Cell V:
330.80 ų (Calculated from Unit Cell)
Z:
2
Crystal Structure
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0019787 | Ghiaraite | Leclaire A, Borel M M (1979) Liaisons hydrogene et coordination du calcium dans les cristaux de CaCl2*4H2O alpha Acta Crystallographica B35 585-588 |  | 1979 | synthetic | 0 | 293 |
| 0020228 | Ghiaraite | Thewalt U, Bugg C E (1973) Crystal structure of calcium chloride tetrahydrate Acta Crystallographica B29 615-617 | | 1973 | synthetic | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 6.124 Å | (47) |
| 5.874 Å | (73) |
| 4.600 Å | (88) |
| 3.569 Å | (46) |
| 2.939 Å | (77) |
| 2.717 Å | (88) |
| 2.628 Å | (100) |
| 2.204 Å | (75) |
Comments:
From Type Description.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 45b : [Other oxidized fumarolic minerals] |
Type Occurrence of Ghiaraite
General Appearance of Type Material:
Euhedral isometric very small grains (up to 5–6 μm long) intimately intermixed with chlorocalcite.
Place of Conservation of Type Material:
Reale Museo of Napoli, Napoli, Italy, registration number 16986E5525
Geological Setting of Type Material:
Mount Vesuvius, Italy in voids in the ejecta surface that were exposed to volcanic vapors.
Associated Minerals at Type Locality:
Synonyms of Ghiaraite
Other Language Names for Ghiaraite
Related Minerals - Strunz-mindat Grouping
| 3.BB. | Králíkite | BaCl2 · 2H2O |
| 3.BB.05 | Eriochalcite | CuCl2 · 2H2O |
| 3.BB.10 | Rokühnite | FeCl2 · 2H2O |
| 3.BB.15 | Bischofite | MgCl2 · 6H2O |
| 3.BB.20 | Nickelbischofite | NiCl2 · 6H2O |
| 3.BB.25 | Sinjarite | CaCl2 · 2H2O |
| 3.BB.30 | Antarcticite | CaCl2 · 6H2O |
| 3.BB.35 | Tachyhydrite | CaMg2Cl6 · 12H2O |
| 3.BB.35 | Aravaipaite | Pb3AlF9 · H2O |
Other Information
Special Storage/
Display Requirements:
Display Requirements:
strongly deliquescent when exposed to the air
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Ghiaraite
mindat.org URL:
https://www.mindat.org/min-43592.html
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References for Ghiaraite
Reference List:
Williams, P. A., Hatert, F., Pasero, M., Mills, S. J. (2013) IMA Commission on New Minerals, Nomenclature and Classification. CNMNC Newsletter No. 15. Mineralogical Magazine, 77 (1) 1-12 doi:10.1180/minmag.2013.077.1.01
Localities for Ghiaraite
Showing 3 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
Italy (TL) | |
| Williams et al. (2013) +1 other reference |
| Locality description | |
Russia | |
| webmineral.ru (n.d.) |
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