What you have is a neat little pendant talisman, or portable shrine, a deity in a box with a removable cover and ornamented with a blue enameled foo dog (for protection), a bat (for longevity) and on the cover a shou symbol also for longevity.
It's a little hard to tell the gender of the figure, but because of the lotus flower she's sitting on, I'm almost certain it's meant to be Guanyin (sometimes spelled Kwan Yin) the goddess of compassion, mercy and love in the Buddhist tradition and the equivalent of the Virgin Mary and the Egyptian goddess Isis. She is also a bestower of children -so be careful how you handle her. The lotus flower she's sitting on represents spiritual purity.
The metal is called paktong, (an alloy similar to pewter in the West) that often has a high content of lead which accounts for the weight.
It's not that old. These began coming out of China in the last quarter of the 20th century and yours may even be newer than that.
As for value, not a whole lot I'm afraid. They just haven't been around long enough to have accumulated any premium with collectors.
If you were to see yours for sale in a vintage store, it would have a full retail value of around $75. This is also the replacement value for insurance purposes.
Expect to get 30% - 40% of this if you were to sell at auction or on line (eBay etc).
I do hope this helps!
Please let me know if you'd like me to explain or expand on any of the above, I would be glad to.