For reasons that are not altogether clear or explicit, they came to be used increasingly by rulers as counselors, advisors and tutors and, eventually, to actually run the holy places of Mecca and Medina, where they were treated with enormous respect. One can speculate on the motivation -- if they were not sexually active or preoccupied they were more likely to be devoted and loyal or given to spiritual preoccupations instead of bodily ones.
Were there other types of white slaves in Islam?
Yes. The Atlantic trade didn't deal with white slaves, but the Islamic trade dealt with large numbers of white slaves.
And in Islam black slaves were never used for the same purposes that they were used in America?
In the early stages of Islam, they were used in the American way. In southern Iraq and neighboring Iran they were put to work in large quantities to clear the salt crust for agriculture and plantation labor. But in the ninth century, a prophet arrived who instigated a rebellion among the black slaves, the Zanj, in the area. This rebellion was enormous. It destroyed much of the commercial shipping in the region and came close to capturing the city of Baghdad, then the greatest city of Islam. It was eventually crushed after quite a protracted period. The impact across Islam was enormous. There developed a reluctance to allow very large concentrations of slaves for plantation agriculture. That is a parenthetical reason for the overwhelmingly domestic nature of the Islamic trade.
Does the Koran specify how slaves should be treated?
The Koran is the key. The relationship between slave and master in Islam is a very different relationship from that between the American plantation laborer and owner. It was a much more personalized relationship and relatively benevolent. Everything here is relative -- being a slave is being a slave and it shouldn't be romanticized.
The institution of slavery is sanctioned in the Koran. To say that the Koran is in any way opposed to the institution of slavery would be wrong. It is never recommended, but it is influentially and explicitly benevolent in its attitude to the poor, the orphaned and slaves. And there is a specific injunction that to free a slave is an act of piety, which has its due reward in the other life.
Incidentally, what was absolutely outlawed in the Koran was to separate an infant or a young child from his mother.
Which was normal in America.
Right. There is a specific statement in the Koran that says that he who separates the child from his mother will himself be separated from his loved ones on the day of judgment.
Since it was an act of piety with immeasurable reward, the incidence of emancipation or enfranchisement was enormously more widespread in Islam than it was in the Western form of slavery. There wasn't a complete separation of master from former slave. Usually, a patron and client relationship developed between slave and master. For example, in Mauritania today there are freed slaves called Haratin whose descendants still pay tribute to the family of the owner. Specifically in the Koran, the owner of a slave is enjoined to provide that slave with an opportunity to purchase his freedom.
There would be a binding contract in which the slave would be provided with the opportunity to earn money for himself and pay in installments to his owner, which by practice, if not by law, became a gratuity. There were then two motivations for freeing your slave -- a reward in heaven and money in this world.
Was slave ownership only for the rich, as it was in America?
Slave ownership was so widespread. Even small shopkeepers owned slaves. Paradoxically, although slaves were at the bottom of the hierarchy because they weren't free, they still stretched right across the economic hierarchy. It was not rare for slaves to become highly prized artists. There were academies that existed to teach young slave girls to play musical instruments. Any self-respecting merchant house would have a chamber orchestra.
Slaves became generals and black slaves became rulers. In the 16th century, a slave, Ambar, became first a general and then the ruler of a large Indian state.
I also thought it was fascinating that the child of a master by a slave was free.
Definitely. A child born fathered by his master was freed, since a child could not be the slave of his parents.
The great numbers of black female slaves must have ensured a great deal of miscegenation.
There's no question about that. It is the major reason for the relatively small size of the black diaspora in Islam, though there were other reasons. A number of countries noted a low fertility rate among black women slaves. And not all women slaves used for domestic purposes had the opportunity to produce children.