Collectors Paradise.

Collectors Paradise.

There are so many minerals coming from Broken Hill in Australia that there is a good chance that many mineral collections will have at least one specimen from there. The street names of the town reflect the importance of the trade to the town.

Prehnite, after laumonite.

Prehnite, after laumonite.

Prehnite is an inosilicate of calcium and aluminium with the formula Ca2AlSi3O12(OH) Although not classed as a zeolite, it is often found associated with minerals which are zeolites such as apophyllite, heulandite, datolite, etc. It's colour varies from light green to yellow, and may be colourless. Crystals of prehnite can be reniform, botryoidal or stalactitic. This specimen is a pseudomorph of prehnite after laumonite, in other words original laumonite has been replaced by prehnite. It's origin is only known as India, but it is probably from the Mumbai district.

Natrolite.

Natrolite.

Natrolite is a  tectosilicate  mineral, in the zeolite group. It is a hydrated sodium and aluminium silicate with the formula  Na2Al2Si3O10 . 2H2O[3] . The specimens locality is not known, but the type locality is basaltic rock.  From a base rock of basalt, prismatic dirty white to colourless crystals, with a hint of green at their bases, have obviously grown into a cavity,

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 mineral 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.  The listed specimens can also be viewed in picture format by accessing the "Bagley collection" on the home page.

Obsidian. Mexico.

Obsidian. Mexico.

Very often referred to as "volcanic glass" Obsidian is neither a rock or a mineral. It is classed as a mineraloid because it is not crystalline. Odsidian is formed in rhyolitic eruptions, and cools so quickly that crystals do not have time to form. Its composition is generally 70% of  SiO2    The three specimens are from Mexico, The larger one is colloquially known as Snowflake obsidian. The snowflake appearance is due to inclusions of spherulites in the form of clusters of radiating crystals of cristobalite. The brown specimen is coloured by trace amounts of iron.