Macuquinas de sagrado corazón
Spanish: In the 1690s, the Potosi mint produced heart-shaped silver cobs often called Hearts of Potosi. Their exvotos form is the Catholic Sacred Heart of Jesus symbol - an asymmetrical heart with flames sometimes coming out of the top. Many had a hole at the top for use as jewelry. They are found in 1/2, 1, 2, 4 and 8 reales demoninations of quite correct coin weights. All are scarce, and the largest are extremely rare. They were also made in the shape of birds and apples or pomegranates. Neither the mint whose workers made them nor the churches that once received some of them as traditional votive offerings have any documentation on these items. Because these coins were within the weight tolerances of their die types, it would seem the mint officials permitted their being made, if only with a wink and a nod. Fake sagrado corazones abound. When they are faked by cutting down an existing Potosi coin, the weight will be wrong for the denomination.
Source: Numiscadero Spanish to English Glossary (Gary Beals)