The 10 Gold Coin is a special kind of coin that's worth ten gold coins as the name implies. It has made appearances in both Mario and Wario games.
Wario Land series
Wario Land: Super Mario Land 3
Wario holding up a 10 Gold Coin in Wario Land: Super Mario Land 3
10 Gold Coins also are present in Wario Land: Super Mario Land 3. In the game, they look like normal coins, but instead of their usual "1" symbol, a cross is stamped on them. They seldom appear after defeating certain enemies in a specific way and when they are collected, they make a unique noise.
Wario can produce this items from his inventory, which will cost him ten of his already collected coins, by pressing the B button and "up" on the directional pad. The coin can then be thrown to defeat enemies. This technique is also necessary to open Goal Doors and completing the Level.
Wario Land II
The 10 Gold Coin also appear in Wario Land II, although they are now called Wario Coins. They appear as golden coins with Wario's face stamped on them and they can be quickly distinguished from other coins by their enormous size. Wario's coin counter increases by ten when he picks up a Wario Coin, and they also make a unique sound when they are collected.
In Wario Land II, coins are used to pay minigames in order to find hidden treasures. Contrary to regular coins that can be found just along the road, Wario Coins are usually stored in secret rooms or hardly accessible locations, to make it harder for the player to obtain them.
Super Mario RPG: Legend of the Seven Stars
Coins that are worth ten regular coins first appeared in Super Mario RPG: Legend of the Seven Stars, along with regular coins and Frog Coins. In this game they look just like regular coins, but are bigger than their normal counterparts. 10 Gold Coins sometimes appear after a larger enemy is bested.
Mario vs. Donkey Kong series
10 Gold Coins reappear in two games in the Mario vs. Donkey Kong series: Mario vs. Donkey Kong 2: March of the Minis and Mario vs. Donkey Kong: Minis March Again!. They are common objects found in many levels. In addition to being worth 10 regular coins, they also give 500 points.
Mario & Luigi: Partners in Time
They also appear in Mario & Luigi: Partners in Time, but instead they are coins with a 10 on them. They are found in ? Blocks and also in the chasm in Thwomp Caverns. They are slightly bigger than regular coins and they give the player ten coins when collected.
New Super Mario Bros. 2
Mario collecting 10 Gold Coins in New Super Mario Bros. 2
10 Gold Coins appear in New Super Mario Bros. 2, where they have almost the exact same design as those of Mario & Luigi: Partners in Time. They are found in Roulette Blocks that produce coins. They are used to distribute 10 coins, 30 coins, and 50 coins.