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Dundasite

Cave Name:

Monte Guisi Cave, Sardinia, Italy

Speleothems:

  • Earthy mass (friable pasty aggregate)

Frequency: Rare

Other geologic settings:

  • Pb-Zn (±Ba) mineralizations of Mississippi-type valley deposits

Location within cave:

  • Left side of the main gallery (~10 m from the bottom of the entrance shaft).

First description of non-cave occurrence:

  • Secondary mineral in the oxidation zone of lead deposits

Other cave locations & References:

  • None

Conservation and Protection:

  • Because of its appearance (earthy mass) it can easily be overlooked, thus, is crucial to preserve all cave deposits along the Main Gallery in Monte Guisi Cave.

Type of rock:

  • Calcic skarn

Age: Cambrian

IMA status: Approved

Group: Carbonates

Chemical formula:
[According to the official IMA-CNMNC List of Mineral Names (http://nrmima.nrm.se/imalist.htm)]

PbAl2(CO3)2(OH)4·H2O

Varieties:

  • -

Habit: acicular, spheroidal aggregates, tufted matted crusts

Color: white, white-greenish

Luster: vitreous, silky

Hardness: 2

Cleavage: perfect {010}

Diagnostic features:

  • effervescent in acids

Identified by:

  • Environmental scanning electron microscope, energy disperssive X-ray

Mineral assemblage:

  • cerussite, hydrozincite, rosasite

Crystal system:
  • Orthorhombic
Cell parameter a (Å): 9.08

Cell parameter b (Å): 16.37

Cell parameter c (Å): 5.62

Cell parameter α (Å): 90

Cell parameter β (Å): 90

Cell parameter γ (Å): 90

Crystal size: sub-millimeter

SEM:

  • tufted matted aggregates
Common crystallographic forms:

  • acicular elongated [001]
Repository:

  • Karst Research Group, School of Geosciences, University of South Florida

General info:

Related References:

  • Moldovan, C., Calugar, M.I., Onac, B.P., de Waele, J., Naseddu, A., Fornós, J.J. 2013. A contribution to the mineralogy of Monte Guisi Cave (SW Sardinia, Italy). Proceedings of the 16th International Congress of Speleology, Brno, 3: 486-489.

  • Beaumont C., Guillemin, C. 1960. La dundasite de Gonnesa (Sardaigne). Bulletin de la Société française de Minéralogie et de Cristallographie, 83 (4-6): 121-124.

Cited in Cave Minerals of the World:
[Hill, C.A. & Forti, P. 1997. Cave Minerals of the World (2nd ed.). National Speleological Society Huntsville, AL, 464 pp.]

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    Cave_mineral_ | by Dr. Radut