This coin has been identified to reasonable certainty, to be a Dà Guān Tōng Bǎo (大觀通寶). The coin is of a cash type, estimated to be of 1 cash value. This currency was a form of "universal currency", issued from 1107-1110 CE. During the 3rd era of Emperor Huizhong (1082-1135). Who was ruler of the Northern Song Dynasty, from 1110-1125 CE.
The coin is made of cast bronze, with a width 25 mm (0.984 in) and an estimated weight of 4 g. This example a has thin-smooth beveled edged rim. Rather than the usual wide rim, common to most cash coins. Some examples may feature a 8-pointed "flower-shaped" hole. Unlike the square-square shape featured by most cash coins, including this example.
Observe
This particular example is notable for it's "melted Hanzi characters.Intially making it relatively difficult to properly identify. Luckily the first character "大" (Dà), made indentification significantly easier. As "Dà" is a relatively uncommon character, within cash coins. Dramatically narrowing the list of possibilities.
The coin's characters are read from top-bottom and left-right. They read "大" (Dà),觀 (Guān), 通 (Tōng), and 寶 (Bǎo). It should be noted that most examples of this coin, will feature much more legible text. Cast in a particular style, known as Slender Gold Script. Said to be based on the Emperor's personal calligraphy.
Historically this coin type was known to produced by 7 mints alone. Located Wanzhou, Hubei, Muzhou, Shuzhou, Wuzhou providences, and the Nanping Army Garrison. One possible reason for this example's "melted Hanzi", is likely due to poor casting methods. As methods were not entirely uniformed between individual mints, which varied in quality and style.
Reverse
The coin's reverse is left bare. Although reverse details were somewhat uncommon, in Northern Song coinage. The coins of succeeding Southern Song (1127-1179), sometimes featured small details. Such as "Star and Moon" patterns, as charms. Occasionally including a single Hanzi character, such as 元(Yuan), 三 (San), and 六 (Liu).
Size Comparison
Additional Notes
The uses of multiple mints was historical common in cash coin production. Creating a large degree of variation, until the machine struck coins of the late-Qing Dynasty (1636-1912 CE).
Historically cash coins were at times made of alternative metals, other than bronze. The common alternatives being brass, copper, and iron.
After the introduction of Kāi-Yuán Tōng-Bǎo coins, in 621 CE. The value of cash coin became based their inscription, rather than their composition.
Bronze ceased being the standard for cash coins in 1505. Cheaper brass becoming the new standard. Coins produced during the late Qing Dynasty contained higher levels of lead and tin, giving them a yellowish tint.