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When we tested hardness, we were trying to scratch the specimen, not break it. For the next two tests, fracture and cleavage, we will be breaking the specimens. We are not looking at how difficult it is to break them. Instead, we will be looking at how they break, especially at the shape of those broken surfaces. Minerals that break in flat, smooth planes have a property called cleavage, and we will look at those in the next test. Any kind of break that is not cleavage is called fracture, and there are several different kinds.
One of the most important tests for identifying a mineral is determining its hardness. After we determine the luster of a mineral, hardness is the test we use to narrow down the possible choices.
This is Oak Tree House at Mesa Verde National Park, built by Native Americans in the year 1250 A.D. They left no written records, and no verbal history survived, so how do we know so precisely when it was built?
In the Southeastern United States, Kudzu vines grow so fast that it seems you can almost see them grow. Still, it is not the fastest growing plant. Which plant is?
