It is originaly Build out of Brick,
The Black Cover has Islamic Desigens and Souar From the Quran on it which is changed once a year.
If you want more more information try the following link:
http://www.mb-soft.com/believe/txh/kaaba.htm
To see some picture go to:
http://entertainment.webshots.com/album/554322859YQLxfX

All the best