Answer: Group
Explanation:
A Group refers to the amalgamation of minerals from several closely related species. It is done for easier classification and is the third tier in Mineral classification with the first being the <em>Variety</em> of the Mineral, the second being the <em>Species</em> and the third being the <em>Group</em>.
An example of a group is Feldspar which is a group of tectosilicate minerals.
The horizontal rows<span> in the </span>periodic table<span> are periods, while the vertical </span>rows<span> are </span>called<span> groups. </span>
The exposed portion of the
continental crust underlying North America refers to Canadian Shield. The continental
crust is known as the North American Craton which consists of rocks from the
Archean dn Proterozoic eons and extends from Mexico to Greenland. Canadian
Shield also produces great resources that helped most humans for their economic
development. Because of the resources present in the Shield, it has a great
disadvantage to settlers. The primary obstacle to population growth in the area
is the presence of the bare rock, thin soils, muskeg and insects.
Finding suitable landfill locations, groundwater pollution, and soil pollution.
