According to Proust (1804), the stone was characterized by a porous structure, dark gray color, and high metal content. All match the description of the fragment from IOM above.

Below are some translations from a document in the archives of the National Museum of Natural Sciences in Madrid (1774):

The fall at Sena took place around noon on November 17, 1773. Three loud detonations were heard and the sounds "frightened farmer's mules so that they stopped eating and began rioting." The smell of sulfur also lingered in the air. Shortly thereafter, a man named Miguel Calvo discovered a mysterious stone on the property of his neighbor, Francisco Gonzalez. He first moved it with his hoe and then by hand, but withdrew immediately because the stone was "very hot." The stone had apparently bounced leaving a shallow hole in the soft ground. Some of the stone was missing and could not be found. After the stone cooled it was brought to Sena, where it was presented to the priest Antonio Pano. The stone was "weighed on a Roman balance and given a weight of nine pounds and one ounce." After news of the stone spread, many residents came to see it and break small pieces off , reducing the weight of the stone to eight pounds and nine ounces. Two days after the fall, a man named Manuel La Cassa found two additional pieces in a garden area of Real Monasterio.

The document maintained by MNCN also mentions that the Mayor of Sixena sent the stone in a box, sealed with the arms of the monastery of Sisters of the Order of St. John, to be within the dominion where the meteorite landed, and opened in the presence of Archbishop Juan Tomas de Micheo.

Interestingly, the fall at Sena remained virtually unnoticed, even by Chladni, until the begining of the 19th century. In 1804, Proust publish a full report, likely prompted by Chladni's epoch making book and the rich discussion on the origin of rocks that were falling from the sky. From here the Sena meteorite would eventually find its way into the museums and institutions around the world. Today less than 3 kilograms is preserved.

References:

Proust, L. (1804) Analisis de Una Piedra Meteorica Caida En Las Inmediaciones de Sixena: En Aragon, El 17 de Noviembre de 1773. Madrid.

MNCN (Arch 169) A. Documentation Manso sent from Zaragoza on February 5, 1774 to Manuel de roda. National Archives of the Museum of Natural Sciences.