Happy Feast Day of the Purity of the Blessed Virgin Mary!
This Feast was observed in certain places, with Apostolic indult, on the third Sunday of October, until the reforms of Pope St. Pius X, which fixed the date for this Feast on the 16th day of the same month. The Feast Day never made the universal Calendar of the Roman Rite, though the Mass is yet to be found in the appendix Missæ propriæ quæ in aliquibus locis celebrari possunt of the Missale Romanum.
The Carmelites, however, kept the Feast Day of the Purity of the Blessed Virgin Mary, as is expected from the Order that so glories to be the first Order founded under the patronage of the same glorious Mother of God. From The Missal According to the Carmelite Rite in Latin and English for Every Day in the Year (Rome: Vatican Polyglot Press, 1953), here is the Mass for the Feast of the Purity of the Blessed Virgin Mary.
May the intercession of the Immaculate Mother of God avail each of us unto the graces of perseverance in the cultivation of the interior life, particularly by purity of heart and the observance of chastity according to our state in life.