Streak Test in Mineralogy

The video tutorial explains the streak test, a method used by scientists to identify minerals by the color of the powdery mark they leave when scraped across a ceramic tile. The tutorial demonstrates the test on various minerals, including calcite, quartz, gypsum, fluorite, hematite, and graphite, highlighting the different streak colors each mineral produces. The streak test is useful for distinguishing minerals that appear similar in color.

What is the purpose of a streak test in mineralogy?

• To find the color of a mineral's streak

• To determine the hardness of a mineral

• To measure the weight of a mineral

• To identify the crystal structure of a mineral

Which color streak does calcite leave on a black tile?

• Green

• Brown

• White

• Black

What common characteristic do calcite, quartz, and gypsum share in their streak test results?

• They all leave a white streak

• They all leave a black streak

• They all leave a brown streak

• They all leave a green streak

What unexpected result was observed when testing fluorite on a black tile?

• It left a green streak

• It left a black streak

• It left a white streak

• It left no streak

Why is it important to use both black and white tiles in a streak test?

• To test the hardness of the mineral

• To see the streak color clearly if it matches the tile color

• To determine the weight of the mineral

• To identify the mineral's crystal structure

What color streak does hematite leave, despite its black appearance?

• Brownish-purple

• White

• Black

• Green

What does the streak test reveal about hematite that might not be obvious from its appearance?

• Its weight

• Its true color

• Its crystal structure

• Its hardness

What is the primary material used in pencils today, as mentioned in the video?

• Ink

• Charcoal

• Graphite

• Lead

Why was lead replaced by graphite in pencils?

• Graphite is cheaper

• Lead was found to be dangerous

• Graphite is more colorful

• Lead is too soft

What color streak does graphite leave?

• Brown

• Black

• Green

• White