The Maria Theresa thaler (MTT) is a silver bullion coin that has been used in world trade continuously since they were first minted in 1741, at that time using the then Reichsthaler standard of 9 thalers to the Vienna mark. In 1750 the thaler was debased to 10 thalers to the Vienna Mark (a weight approximating half a pound of fine silver). The following year the new standard was effectively adopted across the German-speaking world when that standard was accepted formally in the Bavarian monetary convention. It is owing to the date of the Bavarian Monetary convention that many writers erroneously state that the Maria Theresa Thaler was first struck in 1751. It was named after Empress Maria Theresa, who ruled Austria, Hungary, and Bohemia from 1740 to 1780. The word thaler gave rise to daald