I have had a few people ask me about this since I mentioned it in chat a couple of times. I learned this in the Spring of 2005 from an old Priestess who was rather vile and rude but full of knowledge. The events and circumstances leading up to me meeting her and her son spell out quite a tale unto themselves and perhaps I can elaborate on that at another time. Unfortunately I have gotten lax about practicing this as of late and have lost some bones to my set but I intend to rebuild it and continue, especially after the next hunting season.
What is bone casting?
Many of you are familiar with or practice the use of runes, Tarot, tea reading, entrails, etc. and this is just another similar form of divination or seeing. You sit in a predetermined location and direction, North, South, East, or West depending on what the circumstances call for...the bones which are kept in a small pouch are tossed onto the ground or altar. The directions they land and their location within a circle drawn into the dirt represent the answers sought.
I honestly have never researched its origins but the Priestess learned it from her family who came from Belgium...I guess it's not a wild assumption to think it is Germanic or Celtic in origin.
Choosing a set of bones is entirely your choice, and the association of each bone or bone fragment is customizable. I have three of each in my pouch and each has an association that is identified by me and only me.
Deer antler tips
For my own purposes I use the following associations with the directions:
North --knowledge, discovery, wisdom, exploration
South --emotions, familial connections, unity, trust
East --awakening, beginnings, spiritual advancement
West --dreaming, goals, travel, endings
When casting while say, facing North (casting to divine from the spirit of knowledge or discovery) and 2/3 or 3/3 of the bone that I associate with the unseen or the hidden (opossum fingers) lands pointing West or within the Western quadrant of the circle (spirit of goals and achievements) I will be able to use this to make a reading.
There are similar methods of divination such as reading twigs or reading frost but I personally like this one because it has a lot of character because of the animals involved and has a lot of customization involved based on bone choices and their associated meanings. I wouldn't be surprised if some of the witches of the old ways may have even done this with human bones.
Maybe someone can use this, if anyone wants to add anything that would be great, especially if you know any history of the practice. I'm always open to other peoples interpretations of this as well.