Dull etch marks on quartzite countertops can be tricky to deal with. First, it must be realized that the stone is not pure or true quartzite. True quartzite will not etch. Only soft calcite-based stones like marble, travertine, limestone, and onyx commonly etch. Etching on these types of stones is easy to repair with the ETCH REMOVER / Marble Polishing Powder.
However, in some rare instances, it is possible that a quartzite slab contains calcite (like marble) and will etch, but these slabs are not pure quartzite. In nearly all cases of "quartzite" etching the problem is due to a misnaming of the stone type. Quartzite can often look like marble. Sometimes a marble slab is labeled as quartzite and vice versa. So, it can occur where the buyer thinks it is quartzite, but really it is marble.
This isn't done on purpose or to deceive. Depending on how, where, and from whom the stone is purchased there may be some mystery as to exactly what type of stone it is since again... there are true marbles that look very similar to true quartzites and the classification and naming of stone types is not exactly strict.
Another possible issue is the resin applied to most quartzite slabs. This is done to fill voids and help strengthen and support the slab. It is a normal process, but again no strict standard and some resin-coated slabs can have issues with apparent etching.
If you have a dull etch mark on what you think is a quartzite countertop, the only way to determine the type of stone and thus the type of repair possible is to try and use the ETCH REMOVER / Marble Polishing Powder and see if it works. If it does, you have marble. If it doesn't (meaning zero change after several proper applications), then you have quartzite and need to hire a stone restoration professional to refinish it just like granite.
Quartzite is very hard like granite (actually harder), so hand polishing using the Etch Remover won't work like it does on soft stones like marble. Again, if the Etch Remover has no effect, then it is not a product defect. This simply means that the stone is quartzite and not marble, or it's a resin issue, or the problem was not etching to begin with. Trying the Etch Remover is a cheaper test than hiring a pro right away and you may get lucky.
To avoid this above problem when purchasing slabs for a new countertop, use a screwdriver or piece of granite to try and scratch the surface of the "quartzite" slab. Marble is soft and can be scratched. Quartzite cannot be scratched. An even better method is to drip some lemon juice (or other acidic liquid) on the "quartzite". Marble will etch upon contact with acids, but not quartzite. If the slab passes this test, then it is a properly-labeled quartzite and you have a winner.