Welcome to the website of John S. Mason MPhil, Machynlleth, Wales, UK

- research - interpretation - photography - publication - conservation - site assessment -

the product of 25 years experience in the Earth sciences and information/communication technology


Graduating in geology (1985, Aberystwyth), I went on to pursue postgraduate research on the ore-mineralogy of the Central Wales Pb-Ag-Zn-Cu mining district, in between stints volunteering with the British Geological Survey (BGS) and other activities. Writing the work up in the early 1990s, I was awarded an MPhil in 1995.

Much of my geological research interest, since that time, has focused upon the interplay between Welsh mineral deposits and regional geological processes through time. Through working with BGS and with the commercial sector on gold deposits in the Highlands of Scotland, I soon appreciated the importance of approaching mineral deposits in a multidisciplinary manner. Such an approach has proved useful ever since. In recent years I have been involved, among other things, in a reappraisal of intrusive igneous rocks associated with the early Ordovician Rhobell Volcanism of North Wales - the rocks are slightly to horribly altered and mineralised, but we are making good progress!

Central Wales, it turned out, proved to be a far more complex orefield than the literature suggested, in which multiple phases of mineralisation involving not only Pb and Zn but also more exotic elements like Co, Ni and Sb have occurred. Please click here for details.

The relationship between mineralisation and deformation has major connotations in terms of a region's crustal evolution, so it is of particular interest to me, originally encouraged by my discovery in 1997 that the gold-bearing veins of the Dolgellau Gold-belt pre-date the regional, mid-Devonian Acadian deformation. The veins had for many decades been assumed to post-date that deformation. Click here for an account of the geology of the Dolgellau Gold-belt. Click here to learn about another project I am working on - Alpine fissure-veins in North Wales' slate-belt. More recently, I was a key writer of Volume 2 of A Mineralogy of Wales, produced in web format, available here. For a substantial bibliography of Welsh geology and mineralisation please click here. For a list of my scientific publications please click here.

Geology and metallogenesis in Wales
scientific interpretation services
conserving our geological heritage
Graphics & web design
the first UK occurrence of the Ni-Sb sulphide Tucekite from Central Wales
Electron microscope image of unusually crystallised pyrite from North Wales The lead chlorophosphate pyromorphite Banded tuff-turbidite with Alpine fissure-veins, Cwmorthin, N Wales
Tucekite - 1st UK occurrence
Reticulated pyrite - N Wales
Pyromorphite - Mid Wales
Cwmorthin Quarry, N Wales