Mock the Rock
The third and forth graders have been studying geology. We learned the difference between a rock and mineral. A mineral is one ingredient and a rock has many ingredients.
The first activity we did was to help us learn how to identify what's in the mock rock. A mock rock is a fake rock made out of many ingredients. We broke the rock apart with a nail and our fingers. We found out that there were many different ingredients in the mock rock. Some of the ingredients in our mock rock were red pebbles, green pebbles, and shells. Those ingredients would be minerals in a real rock.
Our homeroom class put the remaining dry ingredients into a vial, then poured water into it and let it sit. When we saw it the next time, it had all the thick ingredients in the bottom like sand and leftover pebbles. At the top of the vial there was flour. We thought there was salt in it, so we poured the liquid from the vial into a petrie dish, then let it sit for a day. When we saw it the next time it was very sparkly like crystals but it was really salt. That proved that there was dried up salt in the petrie dish. When we looked at it under a magnifying glass the salt was shaped like squares with X's in it. We really hope we won't forget the mock rock activity.
Caydance, Paige, Jasper
Scratch Test
Geologist uses a second test called the scratch test to identify minerals in a rock. Mohl's Scale is helpful for identifying the hardness of a mineral. With the softest being Talc at 1 and the hardest Diamond at 10. Mohl's Scale goes from 1-10 in order to realize how hard the minerals are.
The steps of a scratch test is:
1. First you need two rocks and tools such as a nail, a penny, and your fingernail.
2. Then you take the rocks and scratch it with each of the tools in order from fingernail to nail.
3. If you can scratch it with your fingernail then it is a scale of 2 as the softest. If you can scratch it with penny then it is a scale of 3. If you can scratch it with a nail it is a scale of 4 as the hardest.
Purpose of scratch test:
The purpose of the scratch test is to find the minerals out of a rock according to the hardest property. In class we identified the hardness of the minerals listed below. Fluorite 4 Calcite 3 Quartz 7 Gypsum 2. We also tested these rocks for hardness. According to our scratch test Mica 1-2 Horneblend 6-7 Feldspar 4-5.
I hope you have learned a lot about the scratch test. Maybe you can try it at home.
By Katie, Dylan, Lucas
Calcite Test:
A third test that scientists use is the calcite test. Calcite, a common mineral, is found in many rocks. This test is a way to determine if calcite is present in the rock.
Calcite is unique because it bubbles when you put it in cold acids, like vinegar and hydrochloric acid. When calcite evaporates it looks like white crystals.
These are the steps for the calcite test.
1. You must find a rock.
2.Put the rock in a cup with cold acid such as vinegar.
3. Look for bubbling around the circumference of the rock and spiraling clouds. That is clear evidence of calcite.
4.If unsure if bubbles are air bubbles or calcite bubbles, then pour the liquid into a petrie dish.
5.Wait until liquid evaporates. If there are white crystals in the dish, that is a sign of calcite. If the inside of the petrie dish looks like soap scum, there is no calcite.
The calcite test helps geologists because they can determine if there is calcite in that rock. And if there isn't, they will go to another test like the scratch test.
By Emma, Erin, Connor, Lea
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