That question asks these questions:
- Is this possible? Unlimited access to minerals, I presume
- What kind of weapon could effectively "gooify" entire cities? Is that a word?
- Is this new goo layer can be used for metal work?
- What is the quality of this goo layer?
- How would a civilization with near medieval technology utilize this layer?
- What kind of effect this weapon would have on environment?
- What would be the condition of "new earth" after global usage of this weapon?
As you can see, each of these questions should be asked in different posts. I must also ask the OP what he means by "gooify". And then, why there is "glass" in the title of the question.
As of current revision, this question cannot be reopened. It is too broad (multiple questions) and unclear.