Calcium deposits can occur pretty much anywhere in the body, generally overlying a bony surface, such as, in your case, the wrist or your collarbone.
Although a common assumption is that the calcium deposits much be related to getting too much calcium in your diet, this is actually not the case. In fact, you would definitely not want to limit the calcium in your diet, as this could predispose you to a lower bone density, setting you up for a risk of bone fractures later in life.
On the other hand, calcium deposits most commonly form as a reaction to a trauma or to chronic irritation. A common occurrence, for example, is to have them develop at the site of an old sports injury
. In the case of a collarbone, they commonly develop after a collarbone fracture
(I am not sure if this is what happened in your case).
Regardless, in most cases, these calcium deposits do not cause any trouble and they do not need to be treated. Sometimes they may be a source of pain; in these cases, it is not a bad idea to discuss potential treatment with a doctor
who, generally, should be an orthopedic specialist. Please talk to a doctor soon.