Joseph is an extremely common name. My uncle is named Joseph Brodsky, and my great grandfather was named Josef Brocki.
'of Brok' gets translated in Polish as 'brocki'
Thank you for the information. In light of this explanation, it would seem more probable that Brocki is derived directly from Brock, although some argue that Brocki could be a mispronounciation of Brodski. According to what I have gathered, Jewish surnames in Eastern Europe began at the beginning of the 19th century, which is not long ago. I am in the process of uncovering my family history via Ancestry.com, etc., but for now, I am only able to trace my Polish origins to Lodz. I hope I am able to clarify this down the road.
Brok, of course.