Martha J. Egan has spent decades rummaging around markets and antique stores across Latin America in search of the rare, carefully crafted devotional pendants called relicarios.

Her hunt has led her to amass more than 400 of the objects — pronounced reh-lee-CAR-yos; in English, reliquaries — and to write two books about what she has come to view as an overlooked genre within the body of religious art created during the Spanish colonization of the New World.

Of course, “there was not much art in the colonial era that was not religious,” said Ms. Egan, 78, who has a bachelor’s degree in Latin American history.

Typically, the pieces (sometimes called medallones or miniaturas) were pendants with painted, carved or printed depictions of favorite saints or the Virgin Mary on both sides, set in metal bezels under glass. Made for people in a range of social and economic classes, some relicarios were plain while others were elaborately decorated; their creators were usually anonymous.

Perhaps because the pieces were worn as personal expressions of devotion, they largely have gone unnoticed, Ms. Egan said.

“Art historians have totally blown them off,” she said during an interview at Casa Perea Art Space, a 19th-century adobe event venue that she owns in Corrales, N.M., a village just outside Albuquerque. The building also houses her folk-art store, Pachamama, which opened 50 years ago and sells handmade items from Latin America, primarily Mexico, Peru and Bolivia.