In Science Class . . .. Weeks of 1/3 and 1/9

Last week, we examined the mineral property of hardness. Student experimented and found that "harder" minerals can scratch softer ones. We scratched four minerals with our fingernail, an aluminum nail, and a paper clip. The hardest mineral, quartz, could not be scratched by any of the tools, while gypsum, the softest, could be scratched by all three tools. We then discussed the Mohs Hardness Scale, which ranks minerals on a scale of 1-10 based on their hardness. Gypsum was a "2" while quartz was a "7." Often times, gemstones like emeralds, rubies, etc are high up on the hardness scale. Diamonds are a "10."

• What minerals were softer? How did you know?
• What mineral was the hardest?
• As we look at the hardness scale, can a "3" scratch a "5" mineral? What about the other way around?

This week, we will be looking at one of the properties of calcite. Calcite is a fairly common mineral found in many rocks. Geologists can test for the presence of calcite by putting a rock in acid. If calcite is present, a chemical reaction will occur, producing bubbles. This week, we will test a number of rocks - marble, sandstone, limestone and basalt - for the presence of the mineral calcite. We also will be discussing uses of these rocks in construction of many recognizable buildings, such as the Washington Monument and CA Capitol Building.

• Which rocks contained calcite? How did you know? (Marble and limestone)
• What is marble used for? Why is this a concern when considering that rain is slightly acidic? (Marble is a common building material. When acidic rain hits buildings, those buildings are slight weathered due to the calcite's reaction with the acid to form carbon dioxide.)

Note: We are moving forward with the Science Fair, which will be on February 2nd. If you have questions, need supplies or presentation boards, please let me know at caitlinjenkins@berkeley.net or give me a call at Emerson on Tuesdays or Thursdays. Thanks!