Minerals: Streak

To perform the streak test, you rub a specimen on a piece of unglazed porcelain tile. Go to your local hardware store, and look at the backs of their floor tiles. You want a tile that is made of porcelain, and the unglazed back should have a white color.

These tiles are very hard (hardness 6.5), and they have a rough surface. As you rub the mineral across that surface, it acts like a file, powdering up some of the mineral. The color of that powdered mineral is its streak color.

Yeast and Sugar, part 1

This time, we will conduct an experiment to measure cellular respiration of yeast when it is fed different sugars. While we tend to think of sucrose (table sugar) when we hear the word sugar, there are actually many different chemicals that fall into that category. As we will see, different sugars have different properties.