Applied mineral exploration methods, hydrothermal fluids, baro-acoustic decrepitation, CO2 rich fluids
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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.

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ECROFI Iceland
     July 2-6

AOGS Singapore
    30 Jul - 4 Aug 2023

SGA Zurich Aug 2023

Comprehensive Geology Conference Calendar

Gold exploration using baro-acoustic decrepitation

K. Burlinson

Burlinson Geochemical Services P/L

Early attempts to use fluid inclusion decrepitation methods for mineral exploration were compromised by a failure to understand the importance of the presence of gas rich inclusions and their thermodynamic behaviour when heated, leading to misinterpretation and the premature demise of the technique.

We know that many gold deposits form from CO2 rich fluids and these fluids can be readily detected using baro-acoustic decrepitation. Consequently we can use decrepitation as a mineral exploration method to locate CO2 rich, potentially auriferous hydrothermal quartz. Using a computerised decrepitation instrument provides quick, cheap, reproducible and objective measurements of CO2 in contrast to the slow, subjective and labour intensive microthermometric techniques. Although the method is best applied to mesothermal deposits formed at high pressures, it does also work with many epithermal deposits. Gas-rich fluid inclusions give a distinctive low temperature decrepitation peak because these inclusions have high internal pressures at room temperature and when heated, the pressure increases linearly with temperature in accordance with the gas law. In contrast, aqueous fluid inclusions have a condensed liquid phase and do not generate high internal pressures until temperatures above their homogenisation temperatures.

Samples from the Waihi epithermal gold deposit, NZ, have been analysed and they show low overall decrepitation intensities, as expected from epithermally formed fluid inclusions, but they clearly show low temperature decrepitation indicating the presence of CO2 rich fluid inclusions. Samples from or near the active workings show low temperature decrepitation caused by CO2 rich inclusions whereas distal samples either from the same vein or from other veins nearby lack this CO2 caused decrepitation peak. This provides a means of evaluating potentially auriferous quartz veins based on their CO2 fluid contents.

Favona vein, Waihi, NZ

At the Brusson mine in northern Italy, alpine quartz veins were mined for their gold content. These mesothermal veins give intense decrepitation with large and prominent low temperature peaks caused by CO2 rich inclusions. The decrepitation patterns can be used to distinguish between quartz samples which otherwise appear to be identical.

Brusson Italy

Baro-acoustic decrepitation can give valuable fluid inclusion data to use in mineral exploration. Many mineral deposits are “fossilized” fluid systems and we can surely benefit by using fluid inclusion information when exploring for them, not merely for forensic analysis of the deposits we have already found.

International Mineralogical Association meeting, Budapest, July 2010

Full oral presentation of this paper

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