I encountered this story sometime between 1960 and 1990.
An invention was made that could convert any matter into useful materials, but with the loss of most of the mass. No one understand how or where the mass disappeared, but no one cared much. In a series of vignettes, people keep asking, "Won't this be a problem someday?" A child who was taken to see an enormous granite quarry that was being used as stock for the converter asked this, and his father just laughed heartily.
But there was a row when the Antarcticans converted so much water as to lower sea level (yeah, I know, that's ironic now). Over the course of many generations, no one even remembered what the Earth used to look like, as so much of it was converted, and records were lost because the old ones were also converted.
At the end of the story, the Earth is down to 2/3 of its original volume and there is still no awareness of any problem.