________ often contain gem-quality crystals of minerals such as beryl and tourmaline and high concentrations of relatively rare elements such as lithium, boron, and beryllium?

________ is a strong, parallel alignment of coarse mica flakes and/or of different mineral bands in a metamorphic rock.

A ________ denotes the purity of gold used in jewelry.

Which one of the following statements is TRUE for an artesian aquifer?

________ often contain gem-quality crystals of minerals such as beryl and tourmaline and high concentrations of relatively rare elements such as lithium, boron, and beryllium?

________ is a strong, parallel alignment of coarse mica flakes and/or of different mineral bands in a metamorphic rock.

Which one of the following statements concerning glacial deposits is NOT true?

Which of the following correctly describes the difference between ferromagnesian and nonferromagnesian silicates?

Which of the following geologic materials would have the highest groundwater velocities and be least effective in removing unwanted pollutants from the water?

The volcanoes and deep valleys of east Africa are related to a ________.