http://www.slaveryinamerica.org/history/hs_es_florida_slavery.htmSpanish Slavery versus English Slavery
Their experiences fighting the Muslims in the 1400s shaped the Spanish view of slavery, which they viewed to be accidental and unnatural rather than a hereditary condition. Following the Moorish Wars, the Spanish and Portuguese imported 100,000 slaves to the Iberian Peninsula. These African slaves assimilated into the Iberian population, and, consequently, the peninsulars (Spanish-born settlers) who colonized Florida typically had at least one African great-great grandparent.
Both the law of the Catholic Church and the Spanish legal code, the 13th century Siete Partidas of King Alfonso X, regarded slaves as humans rather than property. Although Spanish officials assessed slaves on inventories (compiled for wills, lawsuits, and estate settlements) and priced them for sale, they still viewed slaves as moral and legal entities rather than mere commodities (or, as the Dred Scott case would define them, property). The Partidas protected slaves from abusive masters or freeman, and even provided for the removal of slaves from heinous masters. It also allowed slaves to testify in court against their masters.
Because marriage is a holy sacrament of the Catholic Church, it conferred sanctity upon the family unit and prevented the breakup of families. A study of 150 slave sales in West Florida between 1785 and 1800 revealed no instance of a mother being separated from children under the age of 12. However, slave children did cross a legal threshold around age six when assessors assigned them monetary value independent of their mothers.
The cedula (royal proclamation) of 1526 provided that any slave could purchase his or her freedom or coartación. Because church law required that slaves be given holy days off, and there were many such days on the Catholic Church’s calendar, slaves had the opportunity to earn money during this free time. Since the average freedom price was around 400 pesos and daily wage rates were between one-two pesos, it took a long time for slaves to purchase their freedom. Although rare, manumission occurred more frequently under Spanish law than British law.
I seem to recall that "Lies My Teacher Told Me" mentioned that African slaves who escaped in the vicinity of St. Augustine assimilated into Native American tribes, and thus became the first post-Columbian settlers from the Old World.