Flinders is a Dana locality southeast of Melbourne, Victoria, best known for producing large crystals of gmelinite. The basalts are part of the Older Volcanics with a flow near the top of the sequence dated at 42 million years. Zeolites and associated mineralisation occur in vesicles in basalt along the coastline.

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Featured image: Chabazite from Cairns Bay. Photo width is about 7.5mm and a stack of 125 images.

McAndrew and Marsden describe the Older Volcanics in the Flinders area as having olivine present as phenocrysts in a matrix showing flow structure, and consisting of augite, labradorite, iron ore and green glass.

The main mineralised locations in the Flinders area are as follows:

  • West Head (at Flinders township)
  • Little Bird Rock
  • Cairns Bay (previously recorded as Simmons Bay)
  • Bushrangers Bay (includes Elephant Rock)
  • Cape Schanck

Mindat Locality Page

Map of the Flinders area

The Minerals

Albite (var: Oligoclase) recorded from West Head.

Analcime

Colourless prismatic crystals of natrolite on colourless equant analcime crystals from Cairns Bay.

Aragonite

Goethite balls on prismatic aragonite crystals from Cairns Bay. Photo width 2.5mm, stack of 10 photos.

Barite

Barite occurs as colourless to white crystals to 2mm and is usually the last mineral to form. This group is from West Head. Ex Joan Lamond, ex Frank Robinson.

Biotite: no data available for biotite.

Birnessite/Ranciéite

Birnessite/Ranciéite, thought to be from Little Bird Rock, only existed as a single specimen in Museum Victoria when the Zeolites of Victoria was published. This specimen is from Cairns Bay and was found by Glad Rangott in 1993.

Calcite (including ferroan calcite)

A nice little sceptred calcite from Cairns Bay that goes by the name “the lighthouse”. The sceptre measures 0.8mm across. This shot taken with camera plus extension tubes plus closeup rings.

Celestine: Museum of Victoria specimen M39943 listed as on phillipsite and analcime from Cairns Bay.

Chabazite Group (including chabazite-Ca and chabazite-Na)

Colourless-white pseudohexagonal chabazite crystals from Cairns Bay, showing what is generally termed the phacolite habit. The crystals exhibit complex twinning as can be seen on the ones that are side-on (mini hamburgers!). Ex Bernie and Margaret Day Collection M487.

Connellite

Blue connellite balls on natrolite from Cairns Bay. Personally collected in the late 1980s.

Copper

Two small crystals of native copper, one rounded and rough, the other sharp, with natrolite and analcime from Cairns Bay, Flinders, Victoria. Collected by me in the late 1980s from a boulder that produced connellite and paratacamite as well. Photo width 11mm.

Cowlesite

Cowlesite occurs as silky white puffballs and is the rarest zeolite at Flinders.

Cuprite is occasionally found as an alteration of copper crystals.

Digenite: Black platy crystals tentatively identified as digenite (Birch, 1989).

Dolomite

13mm specimen of an unusual-looking dolomite from Cairns Bay. Ex Joan Lamond Micro Collection.

Erionite-Na

Fibrous overgrowths of erionite-Na on levyne. Originally thought to be offretite or a mixture of offretite and erionite.

Ferro-Kaersutite: No data available for ferro-kaersutite.

Fluorapatite

Rounded apatite megacryst from West Head. Analyses of apatites from Flinders indicate a range from hydroxyl-bearing fluorapatite to fluorine-bearing hydroxylapatite. This specimen, ex Joan Lamond Collection, is labelled as fluorapatite.

Gmelinite-Na: Often occurs as an intergrowth of chabazite and gmelinite.

A very nice specimen of gmelinite on natrolite from Cairns Bay. Specimen measures 65x50x40mm and was collected by the late John Stewart, a prolific collector at both Flinders and Phillip Island.

Goethite

Goethite occurs as coatings or balls on other species (eg aragonite, natrolite). This specimen from Cairns Bay.

Gypsum

Gypsum is very uncommon and forms as either a coating or less commonly crystals such as these. Photo width 5mm. Ex Bernie and Margaret Day specimen.

Hydroxylapatite occurs as megacrysts in basalt at West Head. See fluorapatite.

Kaersutite: Museum Victoria Mineralogy Collection specimen – black crystals in basalt.

Laumontite: No data available for laumontite.

Lévyne Group

Pseudohexagonal lévyne crystal with erionite-Na growth.

Magnesite: Reported in 1902 but considered doubtful as no specimens are known to exist (Birch 1989).

Montmorillonite

Montmorillonite on acicular pyrite from West Head. Photo width 2.5mm.

Natrolite

Colourless chabazite crystals impaled on natrolite needles with bladed thomsonite from Little Bird Rock.
More typical white natrolite sprays from Cairns Bay. Ex John Haupt.

Offretite: See erionite-Na

Described by Gottardi and Galli as probably an intergrowth with erionite. But then Passaglia et al determined that practically all “offretite” grown epitaxially on levyne is actually erionite, including those specimens tested from Flinders.

Paratacamite

Nice equant crystals of paratacamite perched on natrolite prisms, Cairns Bay. Photo width 2.5mm.

Phillipsite Group

A ball of white phillipsite crystals from Cairns Bay.

Pyrite

Found as 1mm cubes or needle-like forms at West Head. Montmorillonite globs on acicular pyrite from West Head. Photo width 2.5mm.

Ranciéite: See Birnessite.

Siderite: Recorded as crystals up to 3mm long with chabazite and montmorillonite.

Thomsonite-Ca

Thomsonite-Ca, Cairns Bay, Flinders, Victoria. An attractive specimen with two radial groups of thomsonite crystals, at 90 degrees to one another. Neat! Photo width 11mm.

Unknown Copper Silicate: A transparent green copper silicate (unknown species) coats other copper minerals.

Vivianite: Reported in 1930 but considered doubtful as no specimens are known to exist (Birch 1989).

Zircon: Zircon occurs as phenocrysts in basalt at West Head.

References

  • Birch, W.D. (1975), Chabazite or gmelinite (or both) in basalts from Flinders, Victoria, Australian Mineralogist 1(1).
  • Birch, W.D., and Pearson, J.E. (1982), Copper chloride minerals in basalt from Flinders, Victoria. Australian Mineralogist, 1(39).
  • Birch, W.D. (1988), Zeolites from Phillip Island and Flinders, Victoria. Mineralogical Record, 19(6).
  • Birch, W.D. (1989), Zeolite Minerals of Victoria. The Victorian Mineralogical Society Special Publication No. 2.
  • Birch, W.D. and Henry, D. (1993), Phosphate Minerals of Victoria. The Victorian Mineralogical Society Special Publication No. 3.
  • CoulsellL, R. (1980), Notes on the zeolite – collecting area of Flinders, Victoria, Australia. Australian Mineralogist, 1(33).
  • Gottardi, G. and Galli, E. (1985), Natural Zeolites.
  • Henderson, W.A., and Garland, C.M. (1986), Natrolite arches from Simmon’s Bay, Australia. Mineralogical Record, 17(6).
  • McAndrew, J. and Marsden, M. (1973), Regional Guide to Victorian Geology.
  • Mitchell, S.R. (1930), Zeolites from Flinders. Victorian Naturalist, 47.
  • Passaglia, E.,Artioli, G., and Gualtieri, A. (1998), Crystal chemistry of the zeolites erionite and offretite, American Mineralogist, 83.
  • Tschernich, R. (1992): Zeolites of the World.