Nice find. It is a Catholic medal. The date on it doesn't refer to when it was made but when St Catherine Laboure had a vision of the Blessed Virgin Mary. Here is a quote from a sight that sells similar medals:
" The oval shape of this Miraculous Medal mimics the original image revealed to St. Catherine Laboure on November 27, 1830 by the Blessed Virgin Mary. Our Blessed Mother displayed herself inside an oval-shaped frame, standing upon the world with various rings on her fingers shining rays of light. Around the outside of the frame were the words, “O Mary, conceived without sin, pray for us who have recourse to thee.” This pewter Miraculous Medal necklace is the exact same image as portrayed to St. Catherine and bears with it a promise of blessings to those who wear it with piety. Mary said to Catherine, “Have a medal struck upon this model. Those who wear it will receive great graces, especially if they wear it around the neck.”
