White stuff on basking dock?

[adamlikesbananas]

I was looking at my basking rock in my musk turtle tank a few days ago and happened to noticed that there were some white patches on it.
The white stuff cannot be removed (I've tried to scrub it off) and you can't feel it, it's kinda like the basking dock lost its color in some places.
Is this because I have a heat light on it all the time? (normal one during the day and a infrared one during the night) could it be that my basking dock is too hot? I placed my hand on the rock for a few seconds and it didn't feel that hot.

 

[bmt123]

It looks like hard water I wouldn't worry

 

[adamlikesbananas]

It looks like hard water I wouldn't worry

K thanks.

 

[Levi the Leopard]

i have had aquarium decor loose color and go from brown/greens to white...

doesn't look like a concern. no worries