calcium deposits

I found a lump on my left breast and had an ultrasound done.  The ultrasound was ill defined, but confirmed that it was hard, not fluid.  Went to the general surgeon who said, after examining me, "it does not scream cancer".  I took that as a very good comment.  He sent me on to have a mammogram to help guide him during my biopsy scheduled for next week.  The mammogram showed some calcium deposits.  Do calcium deposits usually turn out to be a bad thing (cancer) or good (no cancer)?  What exactly are calcium deposits and how do they form?

[japdip]

Calcium deposits are sometimes found scattered about in breast tissue; when they are seen in groups or clusters they are cause for concern and need to be biopsied. Since there is a lump and associated calcifications I hesitate to speculate as to whether this may or may not be a malignancy. The biopsy will determine this with 100% certainty.  Regards ...