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Western Elba minerals: Garnet (Grossular), Epidote.

Last Updated: 28th Apr 2014

By Giuliano Bettini

Nowadays, the island of Elba is famous mainly for two kinds of minerals:
- minerals of pegmatites, tourmaline, beryl, etc.;
- eastern Elba minerals, pyrite, hematite, ilvaite etc.
But strangely other places seem to have been forgotten despite their importance in the past.
This short article is devoted to Garnet and Epidote in two places of western Elba (see note at bottom of page):
- Pomonte beach, Campo nell'Elba, Elba Island, Livorno Province, Tuscany, Italy;
- Colle d’Orano La Guardia, Marciana, Elba Island, Livorno Province, Tuscany, Italy.

An old quote is found in Ref: "Italian Mountain Geology , Part I", CS Du Riche Preller , London, Dulau & Co. , 1918 ( the pdf is available on the Internet, at http://storage.lib.uchicago.edu/pres/2014/pres2014-0087.pdf ).
Here you can read:
“Pomonte to Punta Polveraia, 5 km.
This section extends along the west coast by Chiessi and Punta Timone, and is composed of large masses of peridotitic serpentine and metamorphic rocks resting on and against the granite substratum. The granite here forms veins and apophyses in the serpentine, while large dykes and lenticular masses of quartz-porphyry occur in the overlying metamorphic rocks, near Chiessi also in the granite. Near Pomonte, Punta Fornace, and Punta Polveraia occur in the serpentinous rocks the famous Elban specimens of epidote and garnet.”

Other Ref. is: F. Millosevich - I 5000 Elbani del Museo di Firenze – Contributo alla conoscenza della mineralogia dell’isola d’Elba – Firenze (1914). Here both garnets and epidote are described extensively.

More information about the epidote can be found in Ref: Carobbi G,, Rodolico F., 1976. I minerali della Toscana. Leo Olscki Editore, Firenze. Here the sub - locality “Colle d’Orano La Guardia” has been named (such as in Millosevich) “Patresi” and “Mortigliano”.


However, to my knowledge, in many of the latest books on Elba there are very few quotes concerning this.
Or nothing at all.
Nor informations neither photos of these "famous Elban specimens of epidote and garnet from Pomonte and Punta Polveraia".
Anyway I've found some interesting (...for me) specimens in the 90s.
I show here some photos taken from my Galleries.

First of all, I made a map showing the approximate areas.
These are, as you can see, areas at the edge of the granite of Monte Capanne.
Here there are , in the serpentinous and metamorphic rocks , these specimens of epidote and garnet .

The pictures are related to:
a - Grossular, from Pomonte . I found most of these Garnets on the beach;
b - Epidote, from Pomonte;
c - Epidote, loc. Colle d’Orano La Guardia (also named as Patresi – Mortigliano);
d – “Garnet”, loc. Colle d’Orano La Guardia. Almost certainly these are Grossular (Var: Hessonite), but I’m not 100% sure, so I prefer the more generic denomination of “Garnet”.



___________________________________________________________________________________________________________

Note, warning.
The village of Colle d'Orano belongs to the municipality of Marciana, Elba island, in the province of Livorno, region Toscana. The village of Colle d'Orano is 6.18 kilometers far from the same town of Marciana to whom it belongs. To the municipality of Marciana also belongs the localitiy of La Guardia (5.79 km far from Marciana).
The books of mineralogy (especially the older ones) often refer to these two localities, Colle d’Orano, La Guardia, with the names “Patresi” and “Mortigliano”, two other localities names identifying the same area.
I would add, thanks to Michael Kuss, a reference about the Epidote.
Ref: B. Lotti (1886), "Descrizione geologica dell'isola d'Elba".
Lotti wrote about a locality "Monte la Coscia" (on p. 381). He describes it as: "... very extended deposit which splits into two, one towards Mortigliano, the other towards Patresi". Note that on my map "Monte la Coscia", not indicated, is on the sea, westside of Colle d’Orano.






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Comments

Hi Giuliano,

very nice article. I didn't imagine that when laying on the Pomonte beach I'm laying on garnets. Will have a closer look next time, and if I don't disturb other people may hit some stones too.

While reading your article I remembered having heard of veins on the western slopes of Monte Capanne before, so I did some research myself. Finally I found some pointers in Orlandi/Pezzotta (1996) "Minerali dell'isola d'Elba" (OP), in a very brief paragraph on page 227. There, OP give 2 references. Artini (1887) "Epidoto dell'Elba" and for the garnets Lotti (1886) "Descrizione geologica dell'isola d'Elba". Note that both references are older than the two you mentioned. It's interesting that Du Riche Preller doesn't cite any of them (but other articles of Lotti instead). Wasn't he aware of them?

I am left a bit confused about the synonyms of "Colle d'Orano", La Guardia", "Patresi" and "Mortigliano".

Most, I'm confused about "Patresi". Google maps and OpenCycleMap put "Patresi" on top of "La Guardia". On your map I find "Patresi" about 400m south of "La Guardia", about at the position of "Il Mortaio" (ref. OpenCycleMap). Last, my topographic map "Carta Turistica e Dei Sentieri Isola d'Elba" (ed. multigraphic - Florence) calls "Patresi" the entire vast hill slope east south east (uphill) of "La Guardia" (or east of "Il Mortaio"), extending up to about elevation 600 m at "Serraventosa", with the creek "Uviale dei Patresi" defining it's southern border. So, what is the "Patresi" of the Epidotes?

"Mortigliano" is a locality 250 m south of "Colle d'Orano". I can't see how this can be called "Colle d'Orano, La Guardia" today. Or did you mean that in the past "Patresi" was used as a synonym for "La Guardia", and "Colle d'Orano" for "Mortigliano"?

Adding to that, Lotti wrote about a locality "Monte la Coscia" (on p. 381), of which I can't find anything in any map. He describes it as: "... very extended deposit which splits into two, one towards Mortigliano, the other towards Patresi.". Hence, "Monte la Coscia" must be one of the side peaks somewhere over Patresi and Mortigliano. I will ask some locals when visiting Elba.

Anyway, nice research that will renew interest in the neglected western slopes of Monte Capanne.

Michael

Michael Kuss
23rd Apr 2014 8:20pm
Ciao Michael,
mi dispiace per il ritardo, ma solo oggi ho letto il tuo commento.
Ti ringrazio e sono contento che tu abbia apprezzato l’articolo, il quale “renew interest in these neglected western slopes of Monte Capanne”.
Per quanto riguarda le tue attente e interessanti obiezioni, se vuoi posso mandarti via email una mappa dettagliata, da “Isola d’Elba”, 1:30.000, Litografia Artistica Cartografica, Firenze.
Comunque:
1 – il Monte la Coscia è a Ovest di Colle d’Orano, sul mare;
2 – tutti i nomi" Patresi ", " La Guardia ", " Colle d'Orano " e " Mortigliano " non sono sinonimi, ma nomi di differenti località, tutte molto vicine;
3 – la mia mappa è fatta a mano, quindi molto approssimata ma ho cercato di farla il più possibile esatta.
PS: ti dico anche che, nel Rif: Carobbi G,, Rodolico F., 1976. I minerali della Toscana. Leo Olscki Editore, Firenze, alle pagg. 26-28, trovi descrizioni dettagliate e anche disegni degli epidoti (differenti fra loro) di Patresi e Mortigliano.
Ancora grazie e complimenti per le tue interessanti osservazioni e il tuo interesse,
Giuliano.


Giuliano Bettini
27th Apr 2014 1:52am

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