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
