Day 46 : This week I’ll concentrate on samples from the Cleveland Potash mine at Boulby, North Yorkshire.  This is the Boulby Potash. It comes in two forms, a clean ore and a shaly ore, the ‘ore’ in question being sylvinite (a mixture of sylvite KCl and halite NaCl).  Close to a major fault the sylvinite becomes strained and this can be seen in the mineral lineations on the crystals.

Day 31 : Well, I’ve reached the end of the first month of Rock365.  Today I’ve some black and white photography – coal and snow.  I was out this morning scouting a location for some potential geological site management for educational use and it was snowing!  So here is the Cannel Row Coal seam in the snow.  This outcrop, in Apedale Country Park has become extremely degraded over the years and the only remaining exposure of the coal was at the top of a steep, snow covered slope.  The word ‘cannel’ is a corruption of  ‘candle’.  Cannel coal contains a lot of hydrogen so burns with a bright flame and sometimes way carved into a candle shape to be burnt for illumination. The grey band across the top of the coal is a gleyey clay at the base of the soil profile.

Day 15 : A piece of "moon rock". Selenite literally means 'Of the Moon' and named after Selene, the Greek goddess of the Moon (the Roman equivalent of whom is Luna). This shouldn't be confused with the 'gem' moonstone which is feldspar.  Selenite is a variety of gypsum (calcium sulphate).  The sample here shows a 'leaf' like habit due to the twinned crystals growing upwards.  The sample is from SE Spain, part of the Messinian (~5.4 Ma) evaporite sequence formed during the 'Messinian Salinity Crisis' where the Mediterranean Sea was cut off from the Atlantic and started to dry up.

Day 13 : Vesicular basalt from Iceland.  I really like the surface textures and being full of small bubble holes it is very light.  I spent a fortnight driving around Iceland’s “ring road” so to be honest I can’t quite remember exactly where the sample originates, but is probably from near the Hekla volcano.

Day 12 : I found this little pyritised ammonite at the bottom of one of my rock drawers.  With the marl matrix rapidly disintegrating unfortunately I don't think this fossil is long for this world so I thought I'd better photograph it now. It is from the Liassic of the UK somewhere, probably Charmouth in Dorset.

Day 11 : The dark mineral here is sphalerite or zincblende, the main or mineral of zinc.  It is mostly zinc sulphide with some iron.  The white mineral is calcite and with the sphalerite forms a vein infilling in Lower Carboniferous Limestone. This sample comes from the old mine spoil dumps between Minera in Clwyd and the wonderfully named World's End in Denbighshire, North Wales.  Minera has home to a major zinc extraction industry that peaked in the late 1880s.

Day 10 : Again from the back garden collection, today’s rock is a conglomerate. I find conglomerates and breccias the most aesthetically pleasing of rocks. This one is from Monkstone Point, Pembrokeshire, Wales and is a conglomerate containing not only vein quartz, but clasts of siderite nodules (iron carbonate), reworked from the underlying Coal Measures.

Day 7 : Today’s mineral deskcrop specimen comes from Cumbria, England close to the Florence Mine. The sample shows the botryoidal (resembling a bunch of grapes) habit of the iron mineral haematite with some minor calcite.

Day 5 : The first of my deskcrops.  This sample of otherwise unremarkable fine-grained grey rhyolite has an important minor component – there is gold in that there rock. The small light coloured specks are native gold.  The rock is from El Guanaco Mine, Santa Catalina, Antofagasta Province, Antofagasta Region, Chile

Day 4: Visiting my mother on the way home from Morocco. Here is one of my old rock collection still sitting on the window sill of my old bedroom. This is the Anglesey Blueschist (560-550Ma) from near Llanfairpwllgwyngyll, Anglesey, North Wales. The type locality is at the base of the Marquis of Anglesey’s monument but this is a protected site and sample collection is prohibited. This sample came from the A55 road cutting, now grassed over.  More details on the mineralogy here.