Hydrothermal Breccia.

Hydrothermal Breccia.

This specimen of breccia is from Henfwlch mine, Nant y Moch reservoir, Ceredigion.  Angular clasts of wall rock are embedded in a matrix mainly composed of  a mineral in the Ankerite/Dolomite series. The brown colour suggests that it is a manesium rich/iron defictent ankerite which is also referred to as ferroan dolomite. This type of specimen is plentiful at this site.

Sapphirine/Anthophyllite

Sapphirine/Anthophyllite

The specimen is composed of two minerals,  Sapphirine and Anthophyllite. Sapphirine is a silicate of magnesium and aluminium, (Mg,Al)8(Al,Si)6O20  The mineral is formed in high temperature metamorphic rock, and the crystal colour is light to dark blue. Anthophyllite  Mg2Mg5Si8O22(OH)2   is an amphibole mineral, with a fibrous crystal habit, and may be classed as an asbestos mineral.

A Bagley collection introduction.

A Bagley collection introduction.

I have a very large basement area, and this photograph is my store of all things geological, including my collection of rocks, fossils, and minerals. There are many hundreds of specimens, and it will take me a long time to put all of them on the website. Many  minerals  have been collected here in the Central Wales Orefield (CWO). Unfortunately many of the sites have been overgrown, or "landscaped", leaving only a handful of local sites which may still yield the odd specimen.

Quartz geode.

Quartz geode.

Quartz, Silicon dioxide,  SiO2 is the most abundant mineral in the Earths surface. Geodes form in gas pockets in volcanic rock, or rounded cavities in sedimentary rock. The process begins with the formation of a  hard shell which lines the cavity. followed by subsequent deposits of minerals from circulating hydrothermal fluids.  This specimen is has the hard outer shell, and a deposit of quartz crystals within the shell. There is a very slight purple hue on some of the crystals deeper inside the geode, which has been broken on both ends. The smaller inset picture is of the rear of the geode. The origin of the specimen is only known to have come from Morocco.  

Calcite, St Austell.

Calcite, St Austell.

Calcie, Calcium carbonate, CaCO3. Calcite comes in so many forms, that most specimens have an appearance that can be attributed to a particular location.  This specimen from St Austell in Cornwall is no exception It has an appearance that I have not seen at any other location.The prismatic druzy crystals are very creamy in colour, They are very tightly packed, and are growing from a base of massive translucent calcite.