This Imperial German coin represents the 4th denomination coin of the Goldmark (1874-1914). Notably Imperial Germany issued gold-backed currency, prior to the Great War (1914-1918). The Goldmark was adopted after the decades long effort, to unify the German Confederation (1815-1866). Which lead to the creation of the Kaiserreich. Coins of this type were minted from 1873-1889.
The coin is a smooth-edged design made of a copper-nickel alloy and weighs 3.8 g. Its dimensions are 21 mm (0.83 in) wide and 1.35 mm (0.053) in thick. Making it slightly larger in size than a US Penny (19.05/0.75 in), in that respect.
Reverse
The reverse depicts the Reichsadler, the symbol of Imperial Germany. Notably the coin uses a larger shield design, than coins minted from 1890-1916. Coins with this large shield design are known as "Type I". While later coins with the small shield are known as "Type II". These later coins can also be identified by their larger eagle wings.
Besides the eagle's tail is a pair of letter "A"s. These letters identify the coin as a Berlin-minted coin. "Type II" coins reuse this same mint mark design. Although coins issued during the late Great War (1916-1918), lack mint marks. Despite being essentially zinc versions of the earlier "Type II" design.
The inner rim features a decorative "corded" pattern.
Observe
The observe is practical in it's design, featuring a large number "10" at its center. This number "10" simply represents the coin's 10 Pfennig value. As supported by the lower portion of the coin's wrap-around text. The upper section reads "DEUTSCHES REICH 1876" (German Empire). Listing the coin's issuing nation and mint year.
A pair of dimples separates the upper and lower portions of the wrap-around text.
Additional Notes
The 10 Pfennig was produced by the Berlin (A), Munich (D), Muldenhütten (E), Stuttgart (F), Karlsruhe (G), and Hamburg (J) mints.
During the outbreak of WWI, there was mass hording of gold and silver, this lead to precious metal coins becoming discontinued.
The second (mid-war) debasement eliminated copper and nickel coinage, to conserve strategic metals for the war effort.