A story about Mars, authorities/new colonists("gringoes") vs "local"/old colonists(humans), and a search for a native aliens base/hideout

What I remember so far:

1. Medium-sized novel
2. Probably written before 90s (at least not later than 1998)
3. Male? author
4. All events happen on Mars (though it may be Venus or even something else)
5. There are two groups of humans:
   • government/military/newly arriving colonists
   • already present colonists/guerillas fighting(or at least actively hindering activities of) the first group, whom they call gringoes or something similarly disparaging
6. For some reason, despite their mutual animosity, both groups have to cooperate (probably against some third power)
7. In the end they find (and probably destroy/disable) alien(native Martian?) base.
8. While investigating the base they find strangely looking/operating alien handheld weapons (one is basically a freeze gun, another shoots shards/lattices of something)