Diatomite is a siliceous sedimentary rock composed mainly of the fossilised skeletal remains of diatoms, which are single-celled organisms related to algae. Diatomite has a porous structure, which makes it ideal for use as insulation or as a filtering material (its primary use). Most Victorian diatomite, however, is too impure for use as a filtering agent. When dry, diatomite has the appearance of chalk but is much lighter and is chemically inert.

Most diatomite deposits in Victoria are found in freshwater lake deposits that have interacted with lava flows. The main deposits are at Lillicur, Newham, Moranding, Redesdale, and Linton (Happy Valley), all in central Victoria. Diatomite in these deposits forms layers between or beneath flows of basalt. Individual diatomite beds are laminated, banded or massive and are generally flat lying and between one and three metres thick. The Moranding deposit was worked in the 1940s by underground and open-cut methods.

Diatomite, historically mined at Lillicur, was used as a carrier for chemicals and as filler material in the manufacture of paints and plastics. There is potential to find further resources that are located underneath basalt cover.

Other Victorian diatomite deposits are at Gisborne, Glengower, Mickleham and Portland.

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Further information


To create your own maps online and in real time, plan exploration activities by viewing land status, or download GIS data to add to your own maps, visit GeoVic.

Map of Victoria showing diatomite occurrences. There are about a dozen occurrences to the north west of Melbourne in an area surrounded by Happy Valley, Lillicur, Redesdale, Moranding, Mickleham. There is also an occurrence near Portland.

Page last updated: 12 Jan 2023