Torr Works Quarry, Cranmore, Mendip, Somerset, England, UKi

Regional Level Types
Torr Works Quarry	Quarry (Active)
Cranmore	Civil Parish
Mendip	Group of Divisions
Somerset	County
England	Constituent Country
UK	Country

Habit: Acicular / hair-like xx

Colour: white, cream, colourless

Fluorescence: n.d.

Description: Occurs as small areas (<2mm) of intergrown hairlike crystals giving a felted appearance. Originally thought to be dundasite, with which it occurs, but dundasite crystals are much thicker and more distinct.

Habit: massive; aggregates of larger (< 10mm x 10mm) tabular crystals

Colour: white

Fluorescence: none

Description: A small number of specimens were recovered in the early 1970's, associated with datolite in the hydrothermal quartz veins at Merehead, not the manganese deposits.

Habit: Bladed laths, hexagonal prismatic, and 'spear' shaped xls

Colour: Mostly colorless or white; occasionally pinkish or greenish.

Fluorescence: Some specimens fluoresce yellow with longwave UV

Description: Aragonite is widespread in small quantities at Merehead. Large masses or crystals are uncommon, however.

Habit: aggregates of honey-yellow prismatic crystals in vein quartz.

Colour: lemon to honey yellow, sometimes appearing mid-brown due to oxide coatings

Fluorescence: n/a

Description: Two specimens of Ardennite were found in 1977 by Chris Parkinson in blocks of loose vein quartz near the #1 and #2 veins. Although written up at the time by Bob Symes the paper was never published. Visually very similar to Salmchâteau material, the chemistry is quite different, being As-rich and V-poor. Turner and Rumsey (2010) found that these specimens of ardennite are chemically almost identical to some material from Salmchâteau. The difference in chemistry originally considered diagnostic happened because the specimen (from S-C) with which the 'Merehead' material was originally compared was found on re-examination to really be ardennite-(V), a species not described at the time of the original comparison. They also found doubts about the provenance of the material, including a ten-year gap between the stated 1977 date of finding and submission of the material to the NHM. The specimens are quite unlike anything else found at Merehead (and in the Mendips in general). More investigation is needed, but unless this mineral is found again in situ, it's occurrence at Merehead must be regarded as highly doubtful.

Habit: aggregates of platy crystals up to 2cm across

Colour: white

Description: The presence of a "blixite-like mineral" found at Merehead Quarry in the Mendips (often labelled as blixite) was subsequently confirmed to be the new mineral, mereheadite. The presence of blixite in the Mendips must be considered doubtful. Analysis of a large number of specimens (see Turner and Rumsey 2010) failed to find a single (genuine) specimen of blixite from anywhere in the Mendips, including Merehead. Most of the yellow material thought to be blixite is in fact paralaurionite.

Habit: Generally massive, occasionally crude xls and xl masses

Colour: shades of pink

Fluorescence: Red (SW) - often very strong and with marked phosphorescence

Description: A ubiquitous gangue mineral at Merehead. Generally disinteresting to collectors apart from its very strong fluorescence, caused by manganese.

Habit: massive

Colour: brass-yellow

Fluorescence: none

Description: A single minute grain of relict chalcopyrite was found in manganese oxides from the pod recovered in July 2005. Specimen is now in the NHM.

Habit: Sprays of acicular crystals, occasionally to over 2 cm.

Colour: Dark green

Fluorescence: None

Habit: coatings, stains

Colour: bright blue

Fluorescence: none

Description: Bright blue coatings found in a manganese pod in June 2006 are an amorphous Cu:Si phase which has the chemistry of chrysocolla. Found with crednerite, wulfenite, aragonite, and cerussite.

Habit: massive

Colour: copper coloured

Fluorescence: none

Description: An old specimen in the NHM collections contains a small amount of native copper, associated with cuprite.

Habit: massive

Colour: in a mixture, but probably very pale blue or white

Fluorescence: n/a

Description: Cotunnite is a constituent of a small number of the light blue alteration haloes found around (darker blue) diaboleite crystals in mendipite. It does not appear in all haloes or alternatively is very sparsely dispersed as discrete 'grains' in a large amount of other material.

Habit: Massive, bladed, platy in calcite

Colour: Very dark green to black

Fluorescence: none

Description: Invariably embedded in calcite, very rarely as free standing crystals. Crednerite is usually covered by an oxidation coating of malachite. Has been recently (2006-06) found replaced by kentrolite. 'Crednerite' has recently been found to be a mixture of at least three, possibly four different phases (see Turner and Rumsey 2010). Two of these predominate in the Mendips. In addition, there are a number of alteration phases that are derived from 'crednerite'. These various phases need further investigation, and proper characterisation.

Habit: massive, granular to fibrous

Colour: brown

Fluorescence: none

Description: Cryptomelane is a constituent of the brownish coloured manganese oxides in the outer zones of some manganese pods at Merehead.

Habit: massive

Colour: red

Fluorescence: none

Description: An old specimen in the NHM collections contains a small amount of cuprite, associated with native copper.

Habit: Massive, botryoidal, fibrous

Colour: creamy white to white

Fluorescence: None

Description: A small number of specimens were recovered in the early 1970's. Datolite is associated with the hydrothermal quartz veins at Merehead, not the manganese deposits.

Habit: generally either powdery or massive; rarely as crude xls

Colour: royal blue (massive, xls); light greyish blue (powdery)

Fluorescence: none

Description: Primary diaboleite occurs as massive areas or crude xls embedded in mendipite, cerussite, aragonite etc. Diaboleite also results from the decomposition of chloroxiphite, and this secondary material forms a light blue powdery halo around the chloroxiphite xls.

Habit: fibrous, acicular xls

Colour: greyish-white

Fluorescence: none

Description: Occurs with alumohydrocalcite in a very small number of specimens collected from #2 vein by the late Richard Barstow, probably in the late 1970's. The crystals are very small - <0.5mm

Habit: Clusters of curved blades

Colour: greenish honey-yellow

Description: Identified in Nov 2005 by EDX. Crystals are typical curved 'blades' in clusters, normally <50 microns in size.

Habit: massive to poorly crystalline

Colour: steel grey

Fluorescence: none

Description: Galena is generally absent at Merehead, having been replaced by Pb secondary minerals associated with the manganese pods.

Habit: botryoidal

Description: A small number of specimens comprised of pale yellow to clear hexagonal prisms were found to be hedyphane, rather than mimetite.

Habit: pseudo-hexagonal xls and plates, often stacked into 'worms'

Colour: pearly white, pale green

Fluorescence: none

Description: Hydrocerussite is associated with cerussite in the manganese pods; crystals of hydrocerussite coated with cerussite or calcite are not uncommon. Large crystal masses are often found just outside the manganese pod in the altered limestone wallrock, as pCO2 needs to be high for hydrocerussite to form. 'Hydrocerussite' has recently been found to be a mixture of at least three, possibly four different phases (see Turner and Rumsey 2010). Two of these predominate in the Mendips. These various phases need further investigation, and proper characterisation.

Habit: Blades and plates in matrix; sometimes as equant to elongated bladed xls in cavities.

Colour: black with a reddish internal tint; sometimes dark brown

Fluorescence: none

Description: Recently (October 2006) identified from manganese pods found on benches F and G at the southwestern end of the quarry. Locally present in some quantity, with exceptional xls up to 5mm in length.

Description: Occurs very sparingly, generally as clear to white grains in (white) mendipite. Laurionite may be more common than realised, as it is very unobtrusive in this environment.

Description: A small number of tiny (<4 micron) balls of a brown Pb-Ti-O phase have been found in a specimen with a mixed Mn-Fe oxide matrix from Merehead. These are almost certainly macedonite, but the small size of the material precludes definitive characterisation. A similar phase on the specimen also contains some Fe, and is likely to be related in some way.

Habit: coatings, small crude xls

Colour: green

Fluorescence: none

Description: Small patches of malachite staining resulting from the oxidation of other Cu minerals are common at Merehead. Well formed xls are uncommon, and small.

Description: A Pb-Si-S phase occurs very rarely at Merehead, forming minute clear hexagonal prisms. This is most likely to be mattheddleite, but there is currently insufficient material for a definitive characterisation.

Habit: Massive, granular, powdery

Colour: yellowish green, greenish brown

Fluorescence: none

Description: Occurs as an alteration product, due to silicification of the Fe oxides surrounding manganese pods, in a Pb rich environment. See also kentrolite.

Habit: massive

Colour: generally dirty white, sometimes pinkish to pinkish-purple

Fluorescence: none

Description: The classic Merehead oxychloride, mendipite was common during the 1970's when #1 vein was being worked. Since about 1980 however, the quantity found has declined and it has not been found since the late 1990's.

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Habit: massive; occasionally crude xls but these are very, very rare

Colour: yellow orange to reddish brown

Fluorescence: occasionally yellow-green (SW) but this may be due to impurities

Description: Originally from manganese-rich pods along 'Vein 2' and from loose blocks believed to have been derived from 'Vein 1'. Recently found in manganese pods on benches F and G in 2005 and 2006 respectively.

Habit: prismatic xx ranging from long and thin to short 'barrels'

Colour: mostly yellow, also white, brown, beige, greenish yellow, red.

Fluorescence: None

Description: Mimetite from Merehead exhibits a wide range of coloration, from white through yellow, green, beige, and brown to red. Invariably these all have similar chemistry, near to end-member (arsenate) mimetite. Phospate and vanadate are low to absent. Pyromorphite and lorettoite - though listed from Merehead - have not been confirmed. Several specimens so labelled were tested and all proved to be mimetite. Microscopic darker red patches in some orange mimetites found in June 2006 have V > As (approximately 7:5) and these patches are technically vanadinite (q.v.).

Description: A Pb-Mg-Si-O phase occurs at Merehead as small clear grains, and this is most likely to be molybdophyllite. It has been noted by other investigators, but has never been found in enough quantity for a definitive characterisation.

Habit: massive

Colour: royal blue

Fluorescence: n/a

Description: Small royal blue patches (<2mm) in datolite/apophyllite matrix. Less than five specimens including probe mounts are known. Existing references to the occurrence of ganomalite are incorrect; all the specimens are nasonite (they do not contain manganese).

Habit: massive

Colour: greyish white to transparent

Fluorescence: none

Description: Paralaurionite generally occurs at Merehead as yellow patches to approx 10mm embedded in mendipite. Nearly all of the 'blixite' from Merehead (and the Mendips in general) is really paralaurionite. Paralaurionite also occurs as clear, white, and grey grains and blebs in mendipite and the calcite-cerussite cavity infill in the Mn-oxides. In this form, it is hard to identify, and is probably rather more common than thought.

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Habit: minute areas of granular material

Colour: red, dark red, black

Fluorescence: none

Description: A very rare minor constituent of the oxychloride suite at Merehead. Only found in #1 vein and always occurs embedded in mendipite.

Description: Most often occurs as a very thin black to reddish film, formed by the alteration of oxychlorides (particularly mendipite) and 'crednerite'. Often found between these minerals and the calcite walls of a pod. The pink colour of some mendipite specimens is due to a Pb oxide, almost certainly plattnerite.

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Habit: Pale yellow, hexagonal bipyramidal crystals.

Colour: pale yellow, white

Description: Although not accepted by the IMA as a valid mineral species, crystals of 'plumbonacrite' to around 2mm, and aggregates of xx to around 5mm have been found at Merehead in association with rickturnerite and mereheadite.

Habit: massive, powdery, xls to ~5mm

Colour: black

Fluorescence: none

Description: One of the major pod-forming Mn-oxides.

Description: A considerable number of supposed specimens of 'pyromorhpite' from Merehead were analysed, and invariably proved to be greenish coloured mimetite. Pyromorphite does not occur at this location. Recent work by soil scientists (see references in Turner and Rumsey (2010) have shown that Mn++ destabilises the pyromorphite structure and prevents its formation. This fact almost certainly explains the absence of pyromorphite within the manganese-oxide hosted deposits.

Habit: massive, crystalline, xls

Colour: generally colourless to white; rarely smoky or amethystine

Fluorescence: none

Description: Quartz is the major mineral in the late stage hydrothermal veins at Merehead. Generally found as massive white vein quartz, but xls do occur from time to time. Most are small (<6mm) but exceptional xls to 4cm were found in April 2002. Amethystine and smoky quartz are rare and when the occur are found in the silicified wallrocks of the hydrothermal veins. The purple colour is presumably due to manganese, and the brown to iron.

Habit: massive

Colour: pink

Fluorescence: none (if it fluoresces, it's mangano-calcite)

Description: True rhodochrosite is rare at Merehead, and when it does occur is massive and a sickly light-brown colour. Most of the pink carbonate found at Merehead is manganocalcite, and sometimes aragonite.

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Habit: Generally as fibrous aggregates. Occasionally as glassy masses. Rarely as individual acicular crystals.

Colour: White, grey, pale green.

Description: Romanechite has been reported as occurring at Merehead, but the study of Turner and Rumsey (2010) failed to find any of this mineral. It may well occur, but is currently best regarded as unproven.

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Habit: powdery

Colour: white

Fluorescence: none

Description: Powdery greyish-white material from a pod excavated in June 2006 is a mixture of saponite and magnesian calcite. Occurs with purplish quartz.

Habit: massive, granular to gel like

Colour: white, blue, pink

Fluorescence: n/a

Description: Late stage silica gel is not uncommon at Merehead. It is completely amorphous and often brightly coloured by small amounts of Cu, Fe, or Mn.

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Habit: massive, platy

Colour: white, brown, yellowish, pink

Fluorescence: none

Description: Originally found as pink platy material from #2 vein, recent finds (2005-6) have yielded specimens that are clear, white, grey, bluish, yellow and brown in colour. Recent specimens are associated with mereheadite, to which it is related.

Habit: None

Colour: dark orange-red

Fluorescence: None

Description: Some small, darker patches in orange mimetite collected in June 2006 have V > As (approx 7:5) and therefore technically are vanadinite. However, the bulk crystal composition is that of a marginally V-enriched mimetite, and no distinct vanadinite crystals have been found to date.

Description: Despite reports, does not occur at Merehead. Specimens have been analysed and found to be weathered chrome yellow paint, presumably from blast hole marking. The material consists predominantly of PbCr04 and fillers uniformly ground to ~1 micron. Traces of Ag, Sn and Ni and a metallic phase composed of EPNS are most likely from the grinding rollers when the paint was prepared.

Habit: Tabular blades in matrix to 2cm, free standing xls to 5mm

Colour: honey brown

Description: Most Merehead (and Mendip) wulfenite occurs as honey-yellow blades in a matrix of mixed carbonates (usually calcite and/or cerussite and/or aragonite). Blades are usually <5mm and most are smaller; smaller specimens tend to be more yellow in colour. Larger blades have been known to occur on two occasions. Honey-yellow blades were found in June 2006, up to 25mm in size with one specimen reaching 75mm (but unfortunately, all had been caught by the blast). An old specimen in the NHM collection contains a single, red-brown blade approximately 70mm in size. These are probably the largest UK specimens of wulfenite. Free-standing crystals are very rare and generally very small.

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