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Photograph A:
Fresh granodiorite, Chuquicamata, Chile.
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Sample: Fresh granodiorite.
Mine: Chuquicamata, Chile. Primary Commodity: Copper (Cu) Deposit Type: Porphyry copper Rocks are the signature – or calling card – of geological processes and it is the job of a geologist to decipher a rock’s signature and unravel its geological history.
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Surprisingly, photo A is not of ‘white noise’ on your TV screen, but a photographed sample containing a mineral called ‘magnetite’. This mineral is of great interest to PhD student Rob Sievwright. Rob’s project focuses on the signature of magnetite associated with porphyry systems.
Por-ph-what?
Sadly, it’s time for some terminology. A porphyry rock – pronounced por-fur-ree – is an igneous rock produced by the cooling of magma. Its ‘signature’ shows a texture that is characterised by having large crystals – termed ‘phenocrysts’ – within a fine grained groundmass.
But why is this relevant?
Well, porphyry deposits are associated with this rock type and that’s a big deal.
Porphyry deposits are the world’s most important source of copper and are also a key source for the metals molybdenum and gold. When you think that copper is a vital component in our everyday lives e.g. wiring in our houses, phones and cars, you begin to understand that knowing all we can about these deposits is crucial to our future exploration for them.
Magnetite – an attractive option
Rob’s PhD aims to establish whether magnetite found in porphyry systems has a specific chemistry – in other words, a specific ‘signature’ – that relates to the metals found in the porphyry system. For example, does magnetite in a copper-rich porphyry system have a different ‘signature’ to magnetite in a molybdenum-rich porphyry system or a copper-molybdenum-rich porphyry system? More importantly, does magnetite in a mineralised porphyry system i.e. containing metals of interest, have a different ‘signature’ to magnetite found in a porphyry system lacking an abundance of copper and/or molybdenum i.e. barren? Time-consuming work, but if Rob finds the answer is ‘yes’, then this could prove a valuable tool to all future geologists doing early stage exploration.
So, magnetite as a potential indicator for porphyry deposits? Sign on the dotted line please…
Visit window eighteen for further signature related research involving the Museum’s ore collection.
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Por-ph-what?
Sadly, it’s time for some terminology. A porphyry rock – pronounced por-fur-ree – is an igneous rock produced by the cooling of magma. Its ‘signature’ shows a texture that is characterised by having large crystals – termed ‘phenocrysts’ – within a fine grained groundmass.
But why is this relevant?
Well, porphyry deposits are associated with this rock type and that’s a big deal.
Porphyry deposits are the world’s most important source of copper and are also a key source for the metals molybdenum and gold. When you think that copper is a vital component in our everyday lives e.g. wiring in our houses, phones and cars, you begin to understand that knowing all we can about these deposits is crucial to our future exploration for them.
Magnetite – an attractive option
Rob’s PhD aims to establish whether magnetite found in porphyry systems has a specific chemistry – in other words, a specific ‘signature’ – that relates to the metals found in the porphyry system. For example, does magnetite in a copper-rich porphyry system have a different ‘signature’ to magnetite in a molybdenum-rich porphyry system or a copper-molybdenum-rich porphyry system? More importantly, does magnetite in a mineralised porphyry system i.e. containing metals of interest, have a different ‘signature’ to magnetite found in a porphyry system lacking an abundance of copper and/or molybdenum i.e. barren? Time-consuming work, but if Rob finds the answer is ‘yes’, then this could prove a valuable tool to all future geologists doing early stage exploration.
So, magnetite as a potential indicator for porphyry deposits? Sign on the dotted line please…
Visit window eighteen for further signature related research involving the Museum’s ore collection.
< Back to calendar