Applied mineral exploration methods, hydrothermal fluids, baro-acoustic decrepitation, CO2 rich fluids
Newest Topics:

New model 216 decreptiometer

Exploration of the Mt. Boppy Au deposit, NSW

Forensic tests on soil samples


Do IOCG deposits form from CO2 fluids?

How CO2 inclusions form from aqueous fluids (UPDATED)

Understanding heterogeneous fluids : why gold is not transported in CO2-only fluids

Gold-quartz deposits form from aqueous - CO2 fluids: NOT from CO2-only fluids

Discussions why H2 analysis by mass spectrometry is wrong


Gold at Okote, Ethiopia

Kalgoorlie Au data

Sangan skarn Fe deposits, Iran

Studies of 6 Pegmatite deposits

A study of the Gejiu tin mine, China

Exploration using palaeo-hydrothermal fluids

Using opaque minerals to understand ore fluids

Understanding baro-acoustic decrepitation.

An introduction to fluid inclusions and mineral exploration applications.

 Interesting Conferences:


ECROFI Iceland
     July 2-6

AOGS Singapore
    30 Jul - 4 Aug 2023

SGA Zurich Aug 2023

Comprehensive Geology Conference Calendar


Abitibi belt, Canada


The Archean deposits in the Abitibi belt, Ontario, Canada have been shown by other workers (T.J. Smith, S.E. Kesler) to have abundant CO2 rich fluid inclusions present. Decrepigrams of samples from numerous deposits in this region show low temperature decrepitation peaks caused by these CO2 rich fluid inclusions, in agreement with this other work. The samples in this figure also show a great range of variation of decrepitation behaviour at higher temperatures.

Decrepitation is a simple means of identifying the veins containing CO2 rich inclusions. Because such veins are strongly correlated with Au mineralization, decrepitation is a useful exploration technique for these types of deposits.



Archean  Au


Archean and Proterozoic Au deposits commonly contain an abundance of CO2 rich fluid inclusions. The Mt. Charlotte and Victory mines are Archean greenstone hosted deposits near Kalgoorlie, WA.  The Enterprise and Cosmo Howley deposits are hosted by proterozoic sediments in NT., Australia.

All of these samples show prominent low temperature decrepitation caused by CO2 rich inclusions. Although this peak is subordinate at Cosmo Howley, it is still quite significant and occurs as a broad region of decrepitation commencing near 200oC.

Note that the sample from Cosmo Howley mine was mapped by the mine geologists as "Chert". However, decrepitation shows that this is actually a quartz sample because  chert samples do not contain measurable fluid inclusions and do not decrepitate. Moreover, chert samples certainly do not contain CO2 rich fluid inclusions as this sample does! In this case, decrepitation enables correction of geological misidentifications. At this mine the entire geological model was based on synsedimentary stratiform Au in cherts, and the decrepitation data shows that this model  was wrong. The deposit is most likely an epigenetic replacement of carbonate horizons by auriferous quartz and the decrepitation data is instrumental in resolving this controversy.



Location Map - Australia



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