Hello from JA
My name is Woody.
I will be glad to assist you today.
I have been servicing ALL Major Brands of Appliances for 35 Years,
and have over 100,000 in home repairs and over 80,000 internet repairs under my belt.
What you are seeing is calcium in the water ,the reason you only see it in the ice is because of two reasons.
When the water freezes into ice the calcium chemical state when it changes from a liquid to a solid, the calcium is now hard and can be seen.
The second reason is because the icemaker mold has accumulated a large amount of this hard calcium.
You will not be able to stop it from happening unless you get a reverse osmosis water filter system, (they remove all minerals from the water) but they are expensive.
So the cheaper way to help you is to #1 replace all the water tubing from the refrigerator water inlet valve to the icemaker
Here that part is .
#2 is to replace the icemaker, here that is .
These parts on this product is not something I recommend a home owner replace unless you are very handy / mechanical.
And now the bad part how ever old the refrigerator is ,is just how long this replacing the parts will fix the issue,because you have not done anything to the water quality coming into the unit .