Answer to Question 1
Answer: The extremely small abundances of extra elements are insufficient to affect the properties shared by all specimens of quartz, such as density, luster, hardness, and cleavage. The presence of trace constituents, however, may affect color. Amethyst contains a tiny amount of iron, turning it purple. Therefore, chemical composition, within narrow ranges of variation, is another defining characteristic of individual minerals. It turns out that composition determines the physical properties of minerals. These properties are determined not only by which elements are present in each mineral, but also by how these elements combine with one another.
Answer to Question 2
Answer: A mineral dominated by ionic bonds dissolves easily in water. Adding acid to water further enhances solubility, because acids contain ions that draw atoms in minerals apart from one another.
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