Last update: 11 December 2016 (added presentation from the Bob Symes Memorial Symposium)
These are the slides from the presentation that I gave at the Robert F. Symes memorial symposium that was held at the Geological Society in London last week (December 8th, 2016). Entitled “Beyond Symesite”, it gives an update on the status of our work into the ‘Symesite Group’ of minerals. A formal group proposal is in the process of being submitted to the IMA CNMMN, so until that is formally approved please regard everything in the file as provisional.
Mineral Relationships in the Mendip Hills
This is our December 2010 paper summarising all the information that we had on the mineralogy of the Mendips - we were literally updating the information until a week before the print date. You can find the paper here. We will update this paper as and when we get new data and release new versions here when this happens. The paper was originally published in the Journal of the Russell Society
Manganese Pod Formation
My original 2006 paper on the formation of the Mendip manganese pods can be found here. Note that the ideas on the age of the hydrothermal event have been revised since this paper was published; we found additional field evidence in the meantime and the revised ideas are summarised in the 2010 Mineral Relationships paper above. The paper was originally published in the Mineralogical Magazine
Checklist of Mendip Minerals
This is our master list of the minerals found in the Mendips and the localities where we can confirm that they have definitely been found, in Microsoft Excel spreadsheet format. It is current as of 21 August 2012. We have been able to verify and confirm the majority of the occurrences given in the historical literature, and have been able to add a significant number of additional minerals to the historical record. Most recently, we have been able to update the list of minerals found at and around Sandford Hill. However, we do not for one second think that this list is complete, so if you can help us to extend it, please get in touch.
The Min Mag paper on the structure and chemistry of mereheadite can be found here.
The Min Mag paper on the structure of chloroxiphite can be found here.
Our proposal for the reinstatement of plumbonacrite as a valid mineral species was approved by the IMA CNMNC in June 2012. The formal paper is in the process of preparation and will be submitted to Min Mag in due course.
This new mineral (and name) were formally approved by the IMA CNMNC (as IMA 2010-034). The formal descriptive paper was published in Min Mag and is available here. Some data and images can be found here.
Our proposal for this new mineral from Merehead was approved in February 2012 (as IMA 2011-091). Named for Mike Rumsey, who discovered the mineral (congratulations, Mike!) it is a very unusual mineral. Chemically [Pb2OF]Cl, it is the first known "fluoroxy"-chloride mineral, where - despite the difference in valency and ion size - fluorine replaces oxygen in the chemical structure. It also has the simplest structure of all known Pb sheet-oxyhalide minerals, and is therefore closest to the 'base' structure of all these compounds.
The formal paper can be found here
Classification of sheet Pb-oxyhalides
Our proposal for the formal recognition of Group status for all sheet Pb-oxyhalides with a structure derived from that of litharge has been drafted for submission to the IMA, and should be submitted shortly. The proposal started life as one for a 'Symesite Group' but the information we have gained since then makes it clear that what actually exists is a supergroup with rumseyite as the parent (= "base") structure, and at least three (sub-) groups of minerals within it. These are provisionally designated the 'Symesite Group', the 'Sahlinite Group', and the 'Vladkrivovichevite Group'.
This remains a work in progress and until it has been formally ratified by the IMA CNMNC the group names remain provisional and should not be reused.
Vladkrivovichevite and Hereroite
The paper formally describing both Hereroite and Vladkrivovichevite has now been published in Min Mag and can be found here. Both minerals are oxyhalides of the "Symesite Group" found at the Kombat Mine, in Namibia. Vladkrivovichevite is a Pb-Mn oxychloride-borate in the with the complex chemistry [Pb32O18][Pb4Mn2O]Cl14(BO3)8·2H2O and hereroite is a Pb oxychloride-arsenate-silicate whose chemistry is [Pb32(O, .)21](AsO4)2[(Si,As,V,Mo]O4)2Cl10
These minerals have very unusual structures, and separate papers on the structures have been submitted for publication in American Mineralogist. These have not yet been published, but the relevant references are:
Work and/or papers are in progress (as of 21 August 2012) on: