What is a key characteristic of volcanic ash?

Volcanic ash is primarily composed of tiny fragments of rock and mineral particles that are expelled during volcanic eruptions. One of its most significant characteristics is that it can be very harmful to human health. When inhaled, volcanic ash can cause respiratory issues, aggravate existing health conditions, and lead to lung problems. Additionally, volcanic ash can irritate the skin and eyes, making it a serious hazard for those exposed to it.

The other characteristics listed do not reflect the true nature of volcanic ash. While it may have a light and fluffy appearance in some instances, it can also be gritty and abrasive. The settling of volcanic ash does not typically form solid rock directly; instead, it can lead to the accumulation of layers over time, which may be compacted and cemented into rock through geological processes. Lastly, volcanic ash is not non-toxic; handling it can pose health risks due to the fine particulate matter it contains. Thus, the understanding of volcanic ash's potential health risks underscores its harmful nature.