Answer:
A. Obsidian
Explanation:
It fits the property described in the question.
It cools so fast that no visible crystal or grain could form. It has high silica Composition, black and glassy. It is also used to make tools with sharp edges
The correct answer is Ganges. It is also known as the Indo-Gangetic Plain and the North Indian Plain.
They give more/additional information about a certain topic of research.
They help learns to know what they may expect to see on the field
The quartz is more resistant to abrasion and chemically more resistant than the feldspar. The result is that the quartz remains in the stream but the feldspar breaks down to clay or is dissolved.
(this is from coursehero.com)
