Mineral Luster and Color

The video tutorial by Professor Dave covers mineral identification focusing on luster and color. It explains how luster, either metallic or non-metallic, helps in identifying minerals. Non-metallic lusters include adamantine, vitreous, pearly, silky, resinous, greasy, and dull. The tutorial also discusses how color, influenced by transition metals and structural defects, can be misleading and how the streak test provides a more reliable identification method.

What is the primary difference between metallic and non-metallic lusters?

• Metallic lusters are always transparent.

• Non-metallic lusters have a higher refractive index.

• Metallic lusters are opaque and shiny.

• Non-metallic lusters are always dull.

Which type of non-metallic luster is characterized by a glass-like appearance?

• Adamantine

• Vitreous

• Pearly

• Silky

What causes the iridescent effect in minerals with a pearly luster?

• High refractive index

• Thin layer of oil on the surface

• Presence of transition metals

• Reflection and refraction off crystallographic planes

How do transition metals affect the color of minerals?

• They increase the refractive index.

• They absorb specific wavelengths of light.

• They make minerals colorless.

• They cause minerals to have a greasy luster.

What is the difference between allochromatic and idiochromatic minerals?

• Idiochromatic minerals are always colorless.

• Idiochromatic minerals contain trace transition metals.

• Allochromatic minerals are self-colored.

• Allochromatic minerals have color due to trace elements.

What is the purpose of a streak test in mineral identification?

• To test the mineral's transparency

• To observe the mineral's color in powdered form

• To determine the mineral's hardness

• To measure the refractive index

Which mineral is known for having a reddish-brown streak despite its varying colors?

• Calcite

• Hematite

• Pyrite

• Quartz