From Building Stone Magazine:

Quartzite is the supermodel of natural stone these days. In many ways, it’s nature’s perfect stone: classically beautiful like marble, but strong and unflappable like granite. Unfortunately, quartzite has been terribly misunderstood by the natural stone industry
and consumers alike. The problem comes down to labeling. Marbles, sandstones, and quartzites are all commonly sold as
quartzite. But, marble, sandstone, and quartzite are different stones with different properties. For example, marble is soft
while quartzite is hard. If a marble is sold as a quartzite, the customer is likely to be disappointed because the stone won’t live
up to expectations. This can lead to customer complaints, rework, and possible damage to one’s professional reputation.

The good news is that this conundrum can easily be solved; simple diagnostic tests can sort marble from quartzite. The use of these
tests is starting to take hold around the stone industry and as a result, the correct stone names are being used more often. But we
still have a ways to go. The better we get at evaluating a stone’s properties, the less likely we are to be misled by word of mouth or an incorrect label.

Read the rest of the article.