Calvat was born on 7 November 1831 in Corps en Isère, France. She was the fourth of ten children to Pierre Calvat, a stonemason and "pitsawyer by trade" who did not hesitate to take whatever job he could find in order to support his family, and Julie Barnaud, his wife. The family was so poor "that the young were sometimes dispatched to beg on the street".
At a very young age, Calvat was hired out to tend the neighbors' cows, where she met Maximin Giraud on the eve of their apparition. From the spring to the fall of 1846 she worked for Jean-Baptiste Pra at Les Ablandins, one of the hamlets of the village of La Salette. She only spoke the regional Occitan dialect and fragmented French. She had neither schooling nor religious instruction, thus she could neither read or write.
On 19 September 1846, it is related that Calvat and Maximin Giraud - who at that time were just teenagers - saw an apparition of the Virgin Mary in the mountains of La Salette. The apparition transmitted both a public message to them, and a personal message to each of them.
The bishop of Grenoble, Philibert de Bruillard, named several commissions to examine the facts. In December 1846, the first commissions were established. One was formed of professors from the major seminary of Grenoble and the other from titulary canons. The latter commission concluded that a more extensive examination was necessary before formulating a judgment. A new inquiry was held from July to September 1847, by two members of the commission, Canon Orcel, the superior of the major seminary, and Canon Rousselot.
A conference on the matter at the bishop's residence took place in November–December 1847. Sixteen members - the vicars general of the diocese, the parish priests of Grenoble and the titulary canons - assembled in the presence of the bishop. The majority concluded to the authenticity of the apparition, after the examination of the report from Rousselot and Urcel. Moreover, the Bishop of Sens had examined very carefully three cures attributed to Our Lady of La Salette that had occurred in the city of Avallon. The local bishop, Mgr. Mellon Jolly, recognized on 4 May 1849, one of the three cures, which had occurred on 21 November 1847, as miraculous.
Mgr. de Bruillard was convinced of the reality of the apparition and authorized the publication of the Rousselot report, which affirmed the reality of the apparition. In his letter of approbation, added as a preface, the bishop of Grenoble declared that he shared the opinion of the majority of the commission which adopted the conclusions of the report.
However, Louis Jacques Maurice de Bonald, the Cardinal Archbishop of Lyon, on whom Grenoble depended, suspected a subterfuge. The Cardinal demanded that the children tell him their secret, saying that he had a mandate from the Pope. The children finally acceded to this demand. Calvat, however, insisted that her text be carried directly to the Pope. It was under these conditions that the Bishop of Grenoble sent two representatives to Rome. The text of the two private secrets were reportedly handed to Pope Pius IX on 18 July 1851, but apparently subsequently lost.
The procedure was favourable, since the mandate of Mgr. de Bruillard, adjusted according to observations of Luigi Lambruschini, Cardinal Prefect of the Sacred Congregation of Rites at Rome, was signed on 18 September 1851, and was published the following 10 November 1851. In it, the bishop of Grenoble promulgated this judgement: "We judge that the apparition of the Holy Virgin to the two shepherds, 19 September 1846 ... in the parish of La Salette ... carries within it all the characteristics of truth, and that the faithful have reason to believe it indubitable and certain."
The motives of the decision, which rested on the work of Rousselot and that of the commission of 1847, were the impossibility of explaining the events, the miracles and the cures in a human manner, as well as the spiritual fruits of the apparition, notably conversions and finally the right expectations and desires of large crowds of priests and faithful.
Later, 16 November 1851, the Bishop of Grenoble published a statement that the mission of the shepherd children had ended and that the matter was now in the hands of the Church. The bishop made it clear that the approval of the Church was only for the original revelation of 1846 and not for any subsequent claims.
La Salette immediately stirred up a great fervour in French society, it also provoked enormous discussions. The little visionaries were somewhat disturbed by the perpetual interrogations, the threats, sometimes violent from political and ecclesiastical opponents, and also the assaults of fervour. Calvat especially was venerated in the manner of a saint, not unlike what happened to Saint Bernadette Soubirous, who, without doubting, defended herself against this. This harmed the equilibrium of the two visionaries. Calvat had difficulty living a stable religious life. Maximin, who entered the seminary, also had difficulties living a normal life.
After the apparition in 1846, Calvat was placed as a boarder in the Sisters of Providence Convent in Corenc close to Grenoble. "As early as November 1847, her directress feared 'that the celebrity that had been thrust upon her might make her conceited'." She entered religion at the age of twenty and in 1850 she became a postulant with this order and in October 1851 she took the veil. While at Corenc she was known to sit down surrounded by enthralled listeners, as she related stories of her childhood.
In May 1853, Bishop de Bruillard died. In early 1854 his replacement refused to grant permission for her to be professed, because he found that she was not spiritually mature enough. Calvat claimed that the real reason for the refusal was that the bishop was aiming to gain the favour of the emperor Napoleon III of France.
Following the bishop’s refusal to permit her to be professed, Calvat was officially allowed to move to a convent of the Sisters of Charity. This order was dedicated to hard practical work in helping the poor, and Calvat met brisk common sense, not flattery or adulation. Calvat continued to speak about the apparitions, and a masonic plot to destroy Catholic France. But after three weeks she was returned to Corps en Isère for further education.
Napoleon III was ruling republican France but royalists were plotting to restore the king of the Catholic country. This political controversy dominated conversation throughout France, with the French church trying to maintain neutrality. Calvat made this difficult for the hierarchy, by continuing to repeat the reputed words of the Virgin Mary and opposing freemasonry. The bishop, aware of Melanie’s fervid and outspoken royalist sympathies, was worried that she would become involved and thereby implicate the following of Our Lady of La Salette in politics. In 1854, Bishop Ginoulhiac wrote that the predictions attributed to Melanie had no basis in fact and had no importance with regard to La Salette as they came after La Salette and had nothing to do with it.
Calvat agreed to the suggestion of an English visiting priest, and was allowed to move to the Carmel at Darlington in England, where she arrived in 1855. This removed her from the French political controversies, so the bishop was pleased to agree to this move. She took temporary vows there in 1856. In 1858 Calvat wrote again to the Pope to transmit that part of the secret she was authorized to reveal in that year. While at Darlington she spoke of a variety of strange events and miracles. The local bishop forbade her to speak publicly about these prophecies. In 1860, she was released from her vow of cloister at the Carmel by the Pope and returned to mainland Europe.
She entered the Congregation of the Sisters of Compassion in Marseille. A sister, Marie, was appointed as her companion. After a stay in their convent of Cephalonia, Greece where she and Sister Marie went to open an orphanage, and a short sojourn at the Carmelite convent of Marseille, she returned to the Sisters of Compassion for a brief period. In October 1864 she was admitted as a novice on condition she kept her identity secret. But she was recognized and her identity was no longer secret. In early 1867 she was officially released from the order and she and her companion then went, following a short stay at Corps and La Salette, to live at Castellamare near Naples in Italy, where she was welcomed by the local bishop. She resided there seventeen years, writing down her secret, including the rule for a future religious foundation. Calvat visited the Sanctuary at La Salette for the last time on 18–19 September 1902.
The house, located in Altamura
, where on 14 December 1904 Mélanie Calvat was found dead.
On 14 December 1904 Calvat was found dead in her home in Altamura, Italy. Mélanie Calvat fled to Altamura, where she never revealed her identity. For the locals, she was just an old French woman who used to go every day to the cathedral for the mass. Her identity was revealed only after her death.
Her remains are buried under a marble column with a bas-relief depicting the Virgin Mary welcoming the shepherdess of La Salette into heaven.