Quote:
these were made for collectors.
Nope, these were issued exclusively for use in the Polish section of Upper Silesia (the part that Poland received after the plebiscite of 1921) where the currency was different. Simples!
The stamps were issued in June 1922 & withdrawn from circulation on 30 April 1923
Given the amount of mint material available on the market you could be excused for thinking these were aimed at the philatelic market, in fact most used stamps are CTO. I have a couple of CTO lower value sheets & if I could find these in Australia then there must be masses of this stuff around. Genuinely used commercial covers are another thing, expect to pay $300-$400 for a grubby one.
The Museum of Posts & Telecommunications in Wroclaw, Poland has published a book illustrating some of the stamp essays they have in their archives. Here's the essay of the miner from the series, pen & ink, 109x132mm

There are three types of paper, white smooth thin & white smooth medium & for the rotary printed mark values, white smooth very thin
Here's the papers page from "Polskie Znaki Pocztowe" 1960

And if you're really into it, the perfs..
