martedì 21 agosto 2012

Lapis Specularis: De Natura Fossilium


 

Tra l'ormai vasta bibliografia sul Lapis Specularis non poteva mancare Georgius Agricola, il famoso autore del 'De re metallica'  sulla natura dei metalli, e del meno famoso ma non meno importante 'De Natura Fossilium' del 1546. Il quinto libro di questa opera è infatti espressamente dedicato ai geodi, alla ematite e alla selenite e infine al lapis specularis. L'autore fa ovviamente riferimento ed intreccia i dati di Plinio e del Dioscoride, cercando di dirimere la confusione tra i termini  gesso, selenite e specularis, che già era grande al  suo tempo:




 While man, through his ingenuity, makes gypsum from lapis specularis, nature on the other hand sometimes makes lapis specularis from gypsum. Its name comes from speculum because it is transparent and, having been polished, will reflect the image of anything on one side. It is called σβληνίτης by certain Greeks either because it was usually found at night when the moon was increasing in size or because it drew within itself the image of the moon at night or because it was pellucid and reflected the exact image of the moon each day showing the increase and decrease in size. Others called it αφροσίληνος because many had become convinced that the moon was made of this mineral just as the ignorant have become convinced of the even greater absurdity that it is foam of the moon.

 ma aggiunge anche molte informazioni personali, legate alla sua origine teutonica, informazioni del 'presente' fuse tra citazioni classiche.  Da lui apprendiamo per esempio le modalità d'uso e la coltivazione dei numerosi giacimenti di gesso nell'europa centrale, in Thuringia e Sassonia:

 You have mentioned these under things that are found here and which can be used in medicine and in our buildings.
...
 Selenite is mined in many places. It is abundant in eastern Spain near the town of Segovia and less abundant in Gaul; in small quantities in Saxony near Hildesheim and toward the base of Mt. Desterus beyond Bunsedorf; abundant in Thuringia two miles from Northusa in the Stei-gerwald valley; abundant in the mountains where the Vicelebii have built their famous and strong fortress of Stein; in small quantities in Misena toward Sala; at Bononia, Italy, where a portion of the walls is made from it and where it is found in many foundations; in Sicily, Cyprus, Phrygia, Cappadocia, Arabia, Egypt and Africa. It is either all white, all black or half white and half black as that mined in Hanover in the vicinity of Francisca at the foot of Mt. Desterus. Some of the white is similar to ophite because of its black spots. This variety is found even today and Theophrastus writes that it came from Egypt in ancient times. The honey-white variety is rare. Most of the white is transparent while all other varieties are either less transparent or opaque.

They are found in several places and along the Elbe river for when it overflows it sometimes carries these minerals. Gypsum is sold by the common people and we use their name. They call lapis specularis 'Mary's Ice,' concerning which Pliny has written most exhaustively, it seems to me. Selenite is well named since it splits with exceptional ease into very thin sheets. At one time Spain pro­duced a large amount of this mineral from an area within one hundred miles of the town of Segovia. Today it is produced in Cyprus, Cappadocia, Sicily and especially Africa.

L'uso del gesso cotto, la creazione di statue di santi, l'intaglio del minerale allo stato nativo:

Pliny writes that Lysistratus of Sicyon, brother of Lysippus, was the first to sculpture the figure of man from this mineral and then cover the figure with wax to free it from any imperfections.6 At Northusa in Thuringia a gray wall has been built from the gypsum that occurs in beds in the vicinity and the wall of the port of Algiers, a town of Mauretania, Africa, is of similar material. Pliny writes that the sourness of wine is reduced through the use of African gypsum. Theophrastus writes that fullers have used this mineral instead of cimolian earth at various times for preparing animal skins. It dries when used as a remedy and has the power of producing a film over any­thing. For that reason it stops the flow of blood when mixed with the white of an egg. Having been burnt and thus made more tenuous it dries more but is less able to produce a film over anything. When drunk it is fatal since it blocks the veins and causes acute constipation.

 Proprio sulle pratiche medicinali collegate all'uso terapeutico del gesso, direttamente mutuate dal Dioscoride e legate alla medicina degli umori di Galeno, ancora per la maggiore nel XVI° secolo, si soffermano molte note che pongono l'accento sulla differenza tra 'gesso' comune e cristalli di 'lapis':

Today certain people take the rough stone from a selenite quarry and after burning it use it in the place of lime. Fragments drunk in sour wine relieve dysentery. If the powder, after burning, is sprinkled on fistulas and ulcers it promotes the growth of flesh.  

Interessante inoltre la citazione su alcune chiese che nella sua epoca, usavano vetrate in lapis:

Since it is transparent they made panes of it, even within the memory of Seneca, and these were placed in windows since they shut out the air and transmitted light. A church in Cosuicus, Saxony, and another in Merseburg, Thuringia, have window panes of this mineral.

Nelle speculazioni circa la 'natura' e l'origine di questo strano materiale, viene riprese l'idea già presente in Plinio dei 'vapori' o 'umori' congelati, che assimila i cristalli al ghiccaio, ma la cosa più interessante è la testimonianza del nome in uso, almeno nell'area linguistica dell'autore, di Ghiaccio di Maria:

There are, in a part of Bononia, Italy, small spotted pieces bound together with the surrounding hard stone that have an appearance very similar to the material which is dug from the deepest parts of the mines in Spain. Also it is found included in rock within the earth and is mined. To date pieces which occur free in nature have not been found that are longer than five feet. Certain ones say that, just as a humor of the earth is frozen into quartz and congealed into a stone, the marrow of the bones of wild animals that fall into certain pits is changed into this mineral by nature after a winter. Occasionally it is found black but it is usually an intense white, when it is quite soft, from the effects of sun and weather. It will not deteriorate, if it is not in­jured, when it is taken from rocks of many genera. They have found a use for the fine material for sprinkling around the outer part of the circus during the games in order to give it a dazzling white color. Pliny writes this about selenite and noth­ing could be more clear. 
...He expresses our opinion when he says that it is frozen like quartz and for that reason is called 'Mary's Ice' (Marieneis

Le stesse informazioni vengono dall'autore ripetute sotto forma di dialogo:

 ...For that reason it is used in windows the same as glass. Such a window can be seen in a certain old church of Marieburg. 
Ancon. "Albertus writes the same and says that in the place of the lead which is used to strengthen the glass, smooth pieces of wood are used. 
Bermannus. "That is right. 
Ancon. "Moreover he writes that he himself had seen such large quantities of it in Germany that they filled wagons with it. He says that it is found in France to­gether with gypsum, a part of which is of the very highest quality. 
 Bermannus. "Albertus is right. When our people suffer from dysentery they take a piece the size of a walnut, powder it, place it in sour wine and drink it. Many people have been cured of sickness in this way. 
Ancon. "It is obviously related to gypsum since the Arabs drink the latter to stop the expectoration of blood, to stop menstrual flow and to cure dysentery. 
Naevius. "Dioscorides writes that gypsum will stop the flow of blood but when drunk causes strangulation. Galen does not give it as a drink but recommends that a plaster be made from gypsum, the white of an egg, fine wheat flour and some pleasant binder and used to stop bleeding. 
Bermannus. "Then it is safer to drink selenite without wine. Up to now, it has in­jured no one and I have seen and heard of many people being helped fey it."

L'uso in edifici religiosi in epoca moderna,  la sua natura 'misteriosa' che viene legata quasi ad un prodigio, un ghiaccio speciale, nonchè l'uso medicinale, fanno di questo materiale un qualcosa di potente in grado di veicolare al tempo stesso cura e protezione; cosa questa del resto già presente nel testo di Pedanio Dioscoride, contemporaneo di Plinio che nella versione tradottati dal Matthioli ci ricorda come:

Dannosi i suoi frammenti a bere per lo mal caduco, portanla al collo le donne per le malie, che appiccata agli alberi aumenti il fruttificar loro

Aumentare i frutti, quasi fosse un gioco di trasparenze e riflessi speculari. Riflessi e rimandi che sembrano tracciare una linea di continuità, un futuro anteriore, rispetto alle odierne terapie alternative. L'odierna cristalloterapia vede infatti proprio nella selenite un veicolo potente per trasmettere e incanalare 'energie'  nonchè connettere l'individuo all'universo, leggendo in questo nuovamente l'antico gioco analogico tra 'luna' e pietra, nonchè tra luce riflessa e moltiplicata. C'è da stupirsi a scoprire quanti cristalli di selenite siano oggi in vendita nella rete globale, con valore d'uso non tanto geologico quanto terapeutico-metafisico. Come diceva Borges, si fa fatica ad inventarsi qualcosa di nuovo. Per concludere, se tra i luoghi antichi d'estrazione anche Agricola riporta l'informazione di Plinio circa l'isola di Cipro, è interessante notare come in un opera geografica di fine '600 sulla detta isola, nella sezione sulle ricchezze e le miniere presenti si faccia riferimento al 'cristallo':

Qui sono miniere d'allume, dello stagno, del ferro, e del zolfo e vi si trovano ancora agate, cristallo, diaspri smeraldi e coralli bianchi e rossi... 

Ovviamente nell'isola di Cipro è ben presente il gesso, tutt'ora sfruttato a livello industriale, e anche la varietà in grandi cristalli di selenite è ben presente, tanto da finire anche su alcuni francobolli commemorativi. Che non sia mai si debba andare anche a Cipro per inseguire le sottili tracce della Pietra di Luna? Perchè no...


p.s.
(ovviamente Agricola non scriveva in inglese, ma come suggerisce il titolo in latino, ma ho creduto più comoda la versione inglese) 

 ©SocietàSpeleologicaSaknusem_2012

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