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Specific Gravity:
1.838 (Calculated)
Crystal System:
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.

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Classification of GhiaraiteHide


Physical Properties of GhiaraiteHide

1.838 g/cm3 (Calculated)

Optical Data of GhiaraiteHide

Biaxial (-)
RI values:
nα = 1.530 nβ = 1.557 nγ = 1.567
Max Birefringence:
δ = 0.037
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
From synthetic material

Chemical Properties of GhiaraiteHide

IMA Formula:
CaCl2 · 4H2O

Crystallography of GhiaraiteHide

Crystal System:
Class (H-M):
1 - Pinacoidal
Space Group:
Cell Parameters:
a = 6.3660 Å, b = 6.5914 Å, c = 8.5568 Å
α = 93.504°, β = 97.778°, γ = 110.557°
a:b:c = 0.966 : 1 : 1.298
Unit Cell V:
330.80 ų (Calculated from Unit Cell)

X-Ray Powder DiffractionHide

Powder Diffraction Data:
From Type Description.

Type Occurrence of GhiaraiteHide

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 GhiaraiteHide

Other InformationHide

Special Storage/
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.

References for GhiaraiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Nestola, F., Rossi, M., Zorzi, F., Lanza, A., Peruzzo, L., Guastoni, A. and Kasatkin, A. (2013) Ghiaraite, IMA 2012-072. CNMNC Newsletter No. 15, February 2013, page 8; Mineralogical Magazine, 77, 1-12.
Rossi, M., Nestola, F., Zorzi, F., Lanza, A., Peruzzo, L., Guastoni, A., & Kasatkin, A. (2014). Ghiaraite: A new mineral from Vesuvius volcano, Naples (Italy). American Mineralogist, 99(2-3), 519-524.

Internet Links for GhiaraiteHide

Localities for GhiaraiteHide

This 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.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for 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). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
Italy (TL)
  • Campania
    • Naples Province
      • Somma-Vesuvius Complex
Nestola, F., Rossi, M., Zorzi, F., Lanza, A., Peruzzo, L., Guastoni, A. and Kasatkin, A. (2013) Ghiaraite, IMA 2012-072. CNMNC Newsletter No. 15, February 2013, page 8; Mineralogical Magazine, 77, 1-12
Mineral and/or Locality  
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