Coined in brass and copper (not gold, sorry Claire!), these 20 heller pieces from German East Africa ('Deutsche Ost Afrika', 'DOA') are very scarce today in better grades.
They are considered emergency issues, and were issued in the Tabora region of what is today Tanzania. During the Great War, German forces captured the capital of the region (also called Tabora) after a tough battle. During the East African Campaign, colonial armed forces of the Belgian Congo (Force Publique) under the command of General Charles Tombeur captured the town on 19 September 1916 after heavy fighting. Local control of the town was reestablished in 1919.
There are several variations of these coins, enough to get the juices flowing in any collector. First, they were minted in copper and brass. Second, the obverse side (with the date) has two forms, denoted A and B. Third, the reverse side has three forms, A, B, and C (check the shapes of the Ls in HELLER). Most of the varieties catalog around the same values, listed below:
average circulated: $15
well preserved: $25
fully uncirculated: $100
Check the various obverse and reverse appearances in our figure. If you can find one of the following combinations, you have a valuable coin:
OBVERSE A, REVERSE B, IN COPPER:
average circulated: $200
well preserved: $350
fully uncirculated: $1000
OBVERSE B, REVERSE A, IN COPPER:
average circulated: $85
well preserved: $150
fully uncirculated: $500
These special coins are valuable only when minted in copper. The brass versions have values as called out in the 'normal coins' table above. There is a good discussion on these coins over at CoinCommunity. Why not try building as set of these for yourself? Only the two cited above will be expensive.
Refer to our 'Important Terminology' page on the top left in order to properly interpret these catalog values. Cleaned, scratched, holed or otherwise damaged coins will be worth much less than these values.