Call the GC....that way there is no finger pointing down the road in case something happens to the top and you get blamed for using something you should't have

100% silicone caulk should be used at the sink/counter joint. It comes in clear, and colors. Chris

Thank you ajc71. My DH did put a call into the contractor while I was typing the message.

And, thank you, Chris. I did not know if it should be latex or silicone caulk. The first thing DH bought said it was "siliconized latex". I guess that was supposed to cover everything. That was the one that went back to the store.

I wouldn't worry about the seal between a copper drop-in sink and soapstone. Even if there were no caulk, there wouldn't be much water penetration.

My GC called back and is coming to fix the problem. Thank you all for you responses.