Maggiani also identified the name Tinia, the Etruscan supreme deity, equivalent to ancient Greece's Zeus or Rome's Jupiter.
However, it appears the sanctuary was dedicated only to Uni, Tinia's female consort.
"It is my understanding that the structure of the line that includes both names has bearing on the matter," archaeologist Gregory Warden, professor emeritus at Southern Methodist University, Dallas, and co-director of the Mugello Valley Archaeological Project, told Discovery News.
He stressed that this is a preliminary reading and further research is necessary.
"Etruscan sanctuaries are often dedicated to more than one deity. And we have possible indications that the cult may have changed in nature. As always, you answer one question but raise many more," Warden added.
Indications that Uni was worshipped at the site comes from the location of the stone's discovery.
"The center of worship was an underground fissure that was ritually treated after the destruction of the temple," Warden said.
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The ritual included placing a temple block in front of the fissure, along with a gold ring and a textile embroidered with gold.
"Underground cults of this type were often associated with female divinities," Warden said.
The abundance of weaving tools and a stunning deposit of gold jewelry discovered in previous excavations, already implied that the patron divinity was female. Four years ago, a unique scene of a goddess giving birth was found on a small fragment from a ceramic vessel.
It was the earliest scene of childbirth in western European art and again pointed to an Etruscan fertility goddess.
Recognizing beyond doubt the deity to which the sanctuary was dedicated would be a unique discovery as very few Etruscan sanctuaries can be conclusively identified.
Considered one of the most religious cultures of the ancient world, the Etruscans began to flourish around 900 B.C., and dominated much of Italy for five centuries.
Known for their art, agriculture, fine metalworking and commerce, they became absorbed into the Roman empire by 300-100 B.C.
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Since their puzzling, non-Indo-European language was virtually extinguished (they left no literature to document their society), the Etruscans have long been considered one of antiquity's great enigmas.
Much of what we know about them comes from their cemeteries. Only the short funerary inscriptions and the richly decorated tombs they left behind have provided clues to reconstruct their history.
Poggio Colla is one of the few sites offering insight into Etruscan life in a non-funerary context. The site spans most of Etruscan history from the seventh to the second century B.C., "It's a discovery that will provide not only valuable information about the nature of sacred practices at Poggio Colla, but also fundamental data for understanding the concepts and rituals of the Etruscans, as well as their writing and perhaps their language," Warden said.
Besides being possibly the longest Etruscan inscription on stone, it is also one of the three longest sacred texts to date.
"We stand a chance of learning something new about Etruscan morphology and syntax, which, for me as a linguist, is the most exciting possibility," Rex Wallace, professor of classics at the University of Massachusetts Amherst, who is also studying the stele, told Discovery News.
The finding will be announced in detail at an exhibit in Florence on Aug. 27 and in a forthcoming paper in the scholarly journal Etruscan Studies.