Domain: culture (Artifact Appraisal and Craftsmanship)
Problem: Please examine the obverse and reverse sides of this copper coin, first determine whether it is an ancient authentic item or a modern replica, and provide sufficient and comprehensive reasons based on the information in the images.
Answer: This coin is an authentic copper currency minted in the Qing Dynasty.
1. The calligraphic style of the coin characters conforms to the minting craftsmanship characteristics of the Baozhe Mint in Zhejiang.
2. The patina presents a natural dark brown color with uneven distribution, formed by natural accumulation during long-term circulation.
3. The aperture is an irregular square hole with a simple and unsophisticated shape.
4. Irregular granular textures left by sand casting can be observed on the field and rim of the coin.