Baryte

Baryte

Pen y Clun mine, Central Wales Orefield. Cream coloured massive Baryte composed of compacted bladed crystals in random directions. A few bladed crystals are apparent and well defined in a vugh, indicating the nature of the crystals which make up the specimen as a whole.

Baryte vugh 1

Baryte vugh 1

Bryntail mine, Nr. Llanidloes, Central Wales Orefield. Pinkish, platey crystals of Baryte lining a vugh in a piece of massive Baryte. The other half of the vugh is also in my collection.

Baryte vugh 2

Baryte vugh 2

Bryntail mine, Nr.Llanidloes, Central Wales Orefield. Pinkish, platey crystals of Baryte lining a vugh in a piece of massive Baryte. The other half of the vugh is also in my collection. This is a close up of Baryte vugh 1.

Baryte.

Baryte.

Gorn mine, Nr. Llanidloes, Central Wales Orefield. Massive Baryte with "cockscomb" crystals on the surface.

Baryte.

Baryte.

Bryntail mine, Central Wales Orefield. One half of a Baryte nodule, brken to reveal massive Baryte with a central vugh of small platy crystals. There are also small areas of minute reticulated crystals within the massive body.

Calcite

Calcite

Nantiago mine, Central wales Orefield. Calcite displaying typical rhomboid form and cleavage. An abundance of this gangue mineral is to be found at the mine.

Calcite

Calcite

Nantiago mine, Central Wales Orefield. A wedge of Calcite displaying cleavage in three directions, parallel to the rhombohedral form. The two outer faces have a coating about 1mm. thick, grey in colour, and scaly in appearance, sometimes overlapping as in fish scales. Calcite is abundant as a gangue mineral at this mine.

Calcite

Calcite

Nantiago mine, Central Wales Orefield. Two specimens. The first has interleaved flattened scalenahedral crystals with weathered surfaces. The second is mainly composed of massive Calcite adjoining a layer of Sphalerite, in which is embedded a fractured rhombohedral Calcite crystal with a prominent growth line.

Calcite dripstone.

Calcite dripstone.

Siglenlas mine, Central Wales Orefield. A delicate construction of Calcite coating a piece of host rock, unusual in that it has come from a mine rather than a limestone cave.

Calcite.

Calcite.

Llanfawr quarry, Llandrindod Wells. From a fault in the quarry this specimen is nothing out of the ordinary, but interesting because it quite clearly shows the typical Calcite form and cleavage.

Calcite.

Calcite.

Dylife mine, Nr. Staylittle, Central Wales Orefield. Two larger flattened rhombohedral crystals,and a scattering of smaller crystals on a bed of fine druzy Quartz.

Chrysocolla 1

Chrysocolla 1

Geufron mine, Central Wales Orefield. Specimens collected from the spoil heaps at the mine. Specimens are abundant and are from the surface or just below. The encrustations are mostly without detail, but sometimes include small areas of globular growth. The encrustations are believed to be Chrysocolla, but will need X-ray diffraction to verify.

Chrysocolla 2

Chrysocolla 2

Geufron mine, Central wales Orefield. Detail enlargement from Chrysocolla 1. The globular nature of some of the encrustation is more apparent. The adjacent mine of Hafod Feddgar has an adit with a very large area of encrustation on both walls and floor which is very similar in appearance.

Dolomite / Quartz

Dolomite / Quartz

Tan y Foel quarry, Cefn Coch, Nr Welshpool, Central Wales. The quarry provides a section through the Wenlock, mid Silurian, sedimentary deposits. The rocks belong to the Penstrowed grits fm. The specimen is an example of material from the occasional fault within the quarry, and shows veins filled with Dolomite and Quartz. A small vugh has allowed the growth of clear Quartz crystals and numerous tiny Dolomite crystals which display the familiar curved faces.

Druzy Quartz

Druzy Quartz

Van mine, Central Wales Orefield. Clusters of small, very fine, well formed Druzy Quartz crystals. The crystals are clear, and only observable under high magnification.

Druzy Quartz and Calcite 1

Druzy Quartz and Calcite 1

Dylife mine, Central Wales Orefield. Clear druzy Quartz crystals with a uniform size of about 1mm. on the front and rear of a piece of host rock. There are several small deposits of Calcite on top of the druzy Quartz. The Quartz and Calcite were deposited from hydrothermal circulating fluids at depth with the Quartz being deposited first. Finer detail of the Calcite is to be seen in Druzy Quartz and Calcite 2.

Druzy Quartz and Calcite 2.

Druzy Quartz and Calcite 2.

Dylife mine, Central Wales Orefield. Detail from Druzy Quartz and Calcite 1. Although the deposits are very small, the cleavage and rhombohedral structure of the Calcite is well observed.

Ferroan Dolomite

Ferroan Dolomite

Dylife mine, Central Wales Orefield. An off white aggregate with typical curved faces on the exposed fracture surface. The host rock on which it is deposited is a brecciated light coloured sandstone. Layering observed in the Dolomite indicates that this is a vein fragment.

Galena on Quartz.

Galena on Quartz.

Dylife mine, Nr. Staylittle, Central Wales Orefield. Pieces of brecciated material with a very fine coating of druzy Quartz, on which are scattered flattened crystals of Galena.The base rock is very light grey in colour.

Galena.

Galena.

Eaglebrook ( Nantycagl ) mine, Nant y moch res. West Wales. Small platelets of Galena grown on a thin bed of extremely fine druzy Quartz.The bed continues under the small piece of the remaining attached rock indicating that this was once a very narrow vein within the rock.

Goethite

Goethite

Aberdaunant mine, Central Wales Orefield. Two, very thin deposits of Goethite on a piece of host rock. The first deposit is pisolitic in nature, and is overlain by the second deposit which is in the form of an encrustation. The encrustation is removed here and there exposing the pisolitic first deposit.

Goethite on Pyrite.

Goethite on Pyrite.

Aberdaunant mine, Central Wales Orefield. Fractured country rock with small cubic Pyrite crystals and Quartz. Most of the Pyrite crystals are encrusted with Goethite which is common at this site.

Hematite

Hematite

Aberdaunant mine, Central Wales Orefield. The host rock appears to be brecciated sandstone. The Hematite, which is deposited on the surface is botryoidal in nature, albeit on a very small scale, and there are a few areas of iridescence, gold and silver in appearance. Also on the specimen is a small area encrusted with numerous very small brown crystals of Quartz.

Hydraulic brecciation.

Hydraulic brecciation.

Bryn y Rafr mine, West Wales. Typical brecciated material from this site, which is a mix of host rock, Quartz, and Sphalerite. The host rock is a fine grained dark mudstone. Brecciation is the result of inwardly exploding walls of deep fractures when there is a sudden decrease of pressure in the hot mineral rich fluids which are circulating through the fracture.

Linarite and Malachite.

Linarite and Malachite.

Geufron mine, Central Wales Orefield. Quartz rich host rock with an encrustation of Malachite overlying deep blue Linarite. Most of the Linarite is an encrustation in the form of tightly compacted crystals. Several radiating sprays of bladed crystals about .5mm. in length can be seen with high magnification.

Marcasite

Marcasite

Bryn y Rafr mine, West Wales. Two halves of a broken specimen. The Marcasite is in massive form with no crystals apparent, and with a pale yellow colour. This mineral is very susceptible to "Pyrite decay" and the specimen is kept in a sealed plastic box with a plentiful supply of Silica sachets.

Marcasite / Quartz

Marcasite / Quartz

Bryn y Rafr mine, West Wales. Country rock with Quartz and Marcasite content. The Marcasite has suffered from "Pyrite decay", breaking down into Sulphuric acid and Hydrous Iron Sulphate, the light coloured deposit on the surface.

Marcasite/Quartz

Marcasite/Quartz

Bryn y Rafr mine, West Wales. A layer of Marcasite, sandwiched between two layers of badly defined druzy Quartz, one layer with much smaller crystals. The Marcasite has suffered Pyrite decay, hence the sulphurous deposits on the surface. Although the specimen is kept in a sealed box with Silica dessicates to halt the decay, a steel label, also in the box is very badly rusted by the chemical reaction.

Mineral assemblage on host rock.

Mineral assemblage on host rock.

Aberdaunant mine, Central Wales Orefield. A deposition of different minerals on two faces of host rock. Fine crystals of Quartz, Fine botryoidal Hematite, and a very small amount of Galena. This type of specimen is not uncommon at Aberdaunant mine.

Pyromorphite

Pyromorphite

Aberdaunant mine, Central Wales Orefield. Apple green, barrel shaped crystals, scattered haphazardly on a base rock which is liberally coated with a mixture of Quartz, Galena, and Goethite/Hematite. Pyromorphite is also found at this mine in globular form, or as encrustations.

Pyromorphite

Pyromorphite

Aberdaunant mine, Central Wales Orefield. Apple green in a globular habit with a sub-columnar structure. The base rock is coated with a mixture of Quartz, Galena, and Goethite/Hematite. Pyromorphite is also found at this mine as small barrel shaped crystals, and as encrustations.

Pyromorphite.

Pyromorphite.

Bwlch Glas mine, Nr. Talybont, West Wales. Some stubby, some elongated, barrel shaped crystals. Colouration mostly light to dark green, but with a few almost colourless crystals.

Quartz

Quartz

Dyife mine Nr Staylittle,Central Wales Orefield. Miscellaneous specimens of Brecciated material, with small Quartz crystals and Druzy Quartz filling the crevices. Collected for simply being"pretty" specimens.

Quartz in brecciated rock.

Quartz in brecciated rock.

Bryn Y Rafr mine, West Wales. Common in Hydrothermal ore deposits, brecciated rock is produced by means of hydraulic brecciation. The walls of host rock within fissures is fractured because of changing pressures in hot circulating mineral rich fluids, and is mixed with minerals precipitating from the fluids as it cools,In this instance Quartz.

Quartz, Druzy var.

Quartz, Druzy var.

Bryn y Rafr mine, Central Wales Orefield. A specimen composed of Druzy Quartz, with a small surface deposit of Hematite. The composition implies that this was a brecciation out of which the host rock has been removed by weathering. The Hematite is minimal and appears to be a later deposition.

Quartz, Hematitic var.

Quartz, Hematitic var.

Aberdaunant mine, Central Wales orefield. Small prismatic crystals in druzy form, with varying degrees of hematitic colouration, from pale red to yellowish brown.

Quartz, Hematitic var.

Quartz, Hematitic var.

Dyfyngwm mine, Nr.Staylittle,Central Wales. Brecciated rock with a vhug of small druzy crystals of Quartz which have been coloured by Hematite.

Quartz.

Quartz.

Ystrad Meurig quarry, Ysbyty Ystwyth, West Wales. Dirty white prismatic crystals of Milky Quartz in a cluster, growing at random angles to the base rock which is a very roughly formed Quartz aggregate. Some of the crystals taper slightly toward the base.

Quartz.

Quartz.

Cwm Fron mine, Nr. Tylwych, Central Wales. At first glance this seam fragment appears to be Calcite, but on testing and closer inspection,it is Quartz. Very irregular intergrown prismatic crystals, some with darkened cores.

Siderite

Siderite

Ystrad Meurig quarry, Ysbyty Ystwyth, West Wales. A saddle shaped aggregate, cream in colour. No crystals are found on this specimen, but rhombohedral cleavage is apparent on the fractured surface.

Siderite 1.

Siderite 1.

Castell mine, West Wales. A concretionary mass of small rhomohedral crystals. The crystals have curved, striated faces, and vary in colour from pale cream to light brown.

Siderite 2.

Siderite 2.

Castell mine, West Wales. A small vugh of rhombohedral Siderite crystals on a different face of the specimen in Siderite 1. The crystals have an almost imperceptible curved face, and very faint striations.

Sphalerite

Sphalerite

Dylife mine, Central Wales Orefield. Brecciated rock from ore deposits, consisting of light grey country rock, possibly limestone with Sphalerite in massive form. Also very fine druzy Quartz and very minor Galena. The Sphalerite is overlying the Quartz in several places, indicating that the Sphalerite was a later deposit.

Sphalerite

Sphalerite

Dylife mine, Central Wales Orefield. Sphalerite in massive form with apparent alignment features. The Sphalerite, which is almost black may have derived it's colour from the presence of Iron.

Sphalerite / Quartz.

Sphalerite / Quartz.

Bryn y Rafr mine, West Wales. Several layers of Sphalerite separated by Quartz. There are no observable crystals in the Sphalerite or the Quartz. The Quartz has reddish staining, which is probably Iron staining.

Sphalerite,Galena and Calcite.1

Sphalerite,Galena and Calcite.1

Nantiago mine, Central wales Orefield. Sphalerite and Galena filling crevices in fractured Calcite. The Sphalerite is a coarse aggregate with a very deep red colouration, and the Galena is mostly in the form of cubo-octahedral crystals. The ratio is approximately 90% to 10% in favour of the Sphalerite.

Sphalerite,Galena and Calcite.2

Sphalerite,Galena and Calcite.2

Nantiago mine, Central Wales Orefield. This is a detail from Sphalerite, Galena, and Calcite 1. The Galena cubo-octahedral crystals are in the lower half of the photograph, and the Sphalerite aggregate is in the upper half.

Witherite.

Witherite.

Gorn mine, Nr. Llanidloes, Central Wales Orefield. Small pieces of Witherite, possibly fragments of much larger pieces. The specimens are translucent, and dark cream in colour with no definite crystals observed. However there are parallel growth lines on most pieces found. The specimens were collected from an overgrown sorting floor at the mine.