1、Metal money was certainly better than salt or shell or stone money.
金屬的貨幣當然要比鹽或是貝殼的或是石頭的貨幣好。

2、Metal money considered as a whole
金屬錢幣總稱

3、But if you have much of it, metal money is hard to carry around.
但是你有太多時，金屬貨幣不方便帶在身上。