Stone experts: What's up with quartzite?
Mostly a curiosity question here: there have been at least a half dozen threads over the past couple of weeks on white/grey quartzite counters (luce di luna, quartzite bianco, white princess, white fantasy, super white, others). There seems to be some consensus out there that quartzite is harder than granite, and most people with first hand experience with quartzite counters report no etching, no staining (in fact one quartzite counter owner just reported that she could "set a bon fire on her quartzite and put it out with vinegar" and it wouldn't damage the stone, lol. However, there are a couple of people out there who have tested samples (some sealed samples, others perhaps not), who say that the quartzite (luce di luna) either etched or stained or both.
This leads to my question: Can a quartzite, even the same type of quartzite, have some slabs or sections that can etch and others that don't? I'm just wondering what I'm missing here, or what I don't get, forgive my ignorance. I would think that all light coloured stone, quartzite, granite, white quartz, etc. could stain if you tried hard enough. But I'm surprised about the reports of etching etc. Anyway, any insight anyone has would be much appreciated.