Tourmaline

Tourmaline

Tourmaline is a crystalline boron silicate mineral. There are several varieties and colours. This specimen of dark black elongated crystals will be described as the schorl var. The matrix is Feldspar with minor quartz. It was collected from Colcerrow quarry in Cornwall.

Calcite ( precipitated )

Calcite ( precipitated )

Calcite  CaCO3 Calcium carbonate in precipitated form. A little bit of a novelty in my collection, this specimen was first collected in liquid form, oozing out of the quarry face at Ystrad Meurig in Ceredigion.  After a few months the specimen hardened as the liquid dried out, leaving calcite in an irregular form. That was back in 2005, and ever since it has hardened even more.

Spodumene

Spodumene

Spodumene ( Kunzite var. ) LiAl(SiO3)2  is a pyroxene mineral, lithium aluminium inosilicate. This specimen of the Kunzite var. of Spodumene displays the usual characteristics, with a very pale pink colouration, striations along it's length, and a pitted surface. The pink colour is the result of traces of manganese, and there is some iridescence at the narrow end of the crystal. Spodumene is a main source of lithium. Unfortunately the origin of the specimen is unknown.

Garnet with Muscovite mica.

Garnet with Muscovite mica.

The two main components of this specimen are almandine garnet, and muscovite mica. There is also some quartz, and dull grey/black amphiboles. The wine red garnet is massive, and only shows fractured surfaces. The muscovite mica is shiny silverish plates, with some pseudo hexagonal plates observed. This specimen should really be listed as a rock rather than a mineral. It's location is from the pegmatites of the Evje area of Norway.

Tourmaline

Tourmaline

Tourmaline is a crystalline boron silicate mineral. The specimen is composed of  black tourmaline in massive granular form, set in granite.The structure of the crystals is not immediately obvious because of the massive nature. The inset central photograph is approx 5 mm  x 5 mm and is taken from the surface of the smaller specimen. The parallel acicular crystals can be seen, but even the longest crystals are only 2 mm in length. The specimens location is only known as Cornwall.