Conclusion: It is not silver.
I took my 2006-D Satin Finish 1c in the same type of pcgs holder and I weighed it and found it weighed 33.36 grams. I then subtracted 2.5 grams (weight of post-1982 cents) and it came out to be 30.86 for the weight of the holder. I took the weight of my coin in the holder and found it weighed 36.56 grams. 36.56-30.86 ended up being 5.7 grams.
Upon inspection with a stereo microscope, I was able to find tiny amounts of copper peeking through the "cracks" in the rimming.
Thank you for your help,
That had stumped me for some time.