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Posted by Harjo Neutkens  
avatar Ferristrunzite
April 14, 2009 07:49AM
Click here to view Best Minerals F and here for Best Minerals A to Z and here for Fast Navigation of completed Best Minerals articles.

Can you help make this a better article? What good localities have we missed? Can you supply pictures of better specimens than those we show here? Can you give us more and better information about the specimens from these localities? Can you supply better geological or historical information on these localities?


Ferristrunzite with Cacoxenite from the Type Locality, Blaton Belgium, FOV 1cm

Ferristrunzite is triclinic, and it could be considered as the oxidation product of ferrostrunzite. It forms aggregates and crusts of light-yellow to brownish prismatic crystals, in random orientations as well as in spherical aggregates. Many crystals are bent or deformed.

Hainaut (Henegouwen; Hennegau) Province, Mons, Blaton, Mont-des-Groseillers

FOV 0,8cm Ferristrunzite,Cacoxenite
FOV 0,3cm Ferristrunzite
FOV 0,8cm Ferristrunzite,Beraunite,Strengite
3,5x2,5x1,5cm Ferristrunzite

In 1956 R. Van Tassel started a comprehensive study of the Mont-des-Groseillers in Blaton, Belgium. Due to the construction of the Nimy-Blaton Canal, an interesting geological profile of 25 m thickness was exposed over a length of nearly 1000 m. This whole zone contained a spectacular phosphate paragenesis.
The first mineral he described was crandallite, and later on a whole list of other minerals followed. One of those was a "manganese-free strunzite". Many years later, in 1983, Peacor et al. described the new mineral and not only confirmed the absence of Mn, but also proved that all the iron present was trivalent, and the X-ray diffraction pattern differed significantly from that of strunzite.
Other minerals that occur at the Blaton site are crandallite, minyulite, strengite, phosphosiderite, cacoxenite, beraunite, rockbridgeite, whitmoreite, mitridatite, vivianite, destinezite, allophane/evansite, gypsum and barite.

It is no longer allowed to collect minerals along the banks of the canal at Mont-des-Grosseillers.

Namur Province, Anhée, Haut-le-Wastia

FOV 0,2cm Ferristrunzite,Cacoxenite
FOV 0,6cm Ferristrunzite,Cacoxenite

Ferristrunzite from Haut-le-Wastia was described by Dillen and Van Goethem in 1990, the small crystals that occur in narrow cracks can get up to up to 1mm long.

North Rhine-Westphalia, Wuppertal, Aprath castle, B224 Road cut

FOV 0,35cm Ferristrunzite,Cacoxenite
FOV 0,4cm Ferristrunzite

During road construction works near the castle of Aprath a small Phosphate mineralised zone was encountered in the slate. Other minerals found on the site where: Cacoxenite, Beraunite and Strengite (the find of Evansite remains questionable) The locality is no longer accessible.

Bavaria, Upper Palatine, Oberpfälzer Wald, Vohenstrauß, Waidhaus, Silbergrube

Aplite quarry working the remains of a now largely eroded granitic pegmatite.
Located 1 km W of Waidhaus and around 10 km ENE of Vohenstrauß.

Can anyone help us with information and photographs of specimens from this locality?

United Kingdom
England, Cornwall, St Agnes District, Perranzabuloe, Gravel Hill Mine

Gravel Hill mine worked the western end of the Great Perran Iron lode. Which has been worked inland by several mines for traced distance of about 5kms. At Gravel Hill the lode was developed by a beach adit and shafts on the cliff top. The lode was also worked about 155mts inland in an opencast called the Big Iron Pit. The Iron lode is crossed by a N-S lead lode worked a short distance to the north in Wheal Phoenix, and East Wheal Golden. Gravel Hill is know to have been at work befor 1728, also in the 1860's; and from 1874-82. Output figures are only avalible for the last working. When it produced about 8000 tons of iron ore, and 30 tons of zinc ore.

Can anyone help us with information and photographs of specimens from this locality?

Wisconsin, Rusk Co., Ladysmith, Flambeau Mine

Mined by Kennecott Copper between 1993 to 1997. Site has since been completely restored. This is the only mining of massive sulfides in Wisconsin (other deposits have been drilled, but there are no plans to mine them). Ore was rich enough to ship directly to the smelters without having to be concentrated.

Can anyone help us with information and photographs of specimens from this locality?

Click here to view Best Minerals F and here for Best Minerals A to Z and here for Fast Navigation of completed Best Minerals articles.

Edited 21 time(s). Last edit at 11/27/2010 11:00PM by Harjo Neutkens.
avatar Re: Ferristrunzite
April 14, 2009 08:53AM
Harjo, Wow, great images. At the rate you are going we will have Best minerals finished in a few years and here I thought I would die long before it was anywhere near finished.

Rock Currier
Crystals not pistols.
avatar Re: Ferristrunzite
September 07, 2014 05:43PM
In the meantime, I improved the locality description of the Gravel Hill mine:

For the geology of the occurrence (which it shares with several other mines in the area), see the Perran Iron Lode:
avatar Re: Ferristrunzite
September 07, 2014 08:38PM
Great article so far Harjo! :)

A few remarks though:

- you mention that Peacor described the mineral in 1983.

- The mineral page itself here on Mindat says it was discovered in 1986 and named in 1987.

- the article "Minerals with Belgian type localities" in the Geonieuws issue of October 2013 (which is available for free here: for which I myself did the translation, states:

" This mineral had been known from the locality of Blaton for some time before the American Peacor finally described it and subsequently submitted it to the IMA in 1987. " AND "In 1966, Van Tassel described a number of phosphates occuring at Blaton (strengite, phosphosiderite, cacoxenite, and strunzite). This article was in fact the start of the research of ferristrunzite. Van Tassel namely already distinguished between (manganese-free) strunzite and strunzite from most other localities. He wrote, “An analogy between the composition of the manganese-bearing strunzite from Hagendorf, the one from Seixeira and the mineral from Blaton is not easily clarified. The available analyses are still too rare and even too variable (the analysis of the mineral from Blaton is the first for a non-manganese-bearing strunzite) to justify, at this moment, the specific distinction between the Belgian mineral and strunzite.”

My question: what year do we put as "discovery", "description", "submission to IMA" and "approval by IMA"?


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