The amount fields in Operations/VirtualOperations are still strings unfortunately (todo: have native types everywhere for v2).

So what you have to do is query all transactions for a time period, and then filter out the ones you need in your code.

Python Example:
```
from steem.amount import Amount

filter(Amount(x['amount']).currency == 'STEEM', lambda x: Amount(x['amount']).amount > 100, db_results)
```