Find oldest and newest date by grouped material in 2 columns...

Well the title is probably very confusing but hoping the workbook helps.

You see 4 data lines of 2 materials.
So the macro should look for every material separate what the highest en lowest date is in columns I and J.
Then in column K give these dates as a "key"
For the first material this would be > 07/27/2016 - < 12/19/2021
So bigger then "-" smaller then (so a range).

Also the date format must be American as the input is European

The list is much longer and some material are in 4 times or even 6 times or only once.
But list is already sorted on material number so they are already grouped.