Marbling is a way of processing wet paint images by drawing out colours in wavy lines. The technique was used of old to create the pretty patterns you see in the bookends of antique or fine books.
This image is based on Glass Brick 1 using the marbling tool in Corel Painter, one of those addictive toys that is great fun to play with. This one is based on multiple iterations in various directions.
Thank you for taking the time to look. I hope you enjoy the image!
PS Depending on your device this is nicer zoomed in : press Z if you wish :)