 Now we're going to talk about the mineral property of cleavage, and I've got this sample here And it's kind of rough and it's got some different sides on it And we're going to put this into a box just for some shielding and we're going to try and break it Now when I use the hammer rather than using the flat side of the hammer I'm going to try and use this pointed side of the hammer to see if I can get a clean break Doesn't always work on the first time, but we'll see what we can get here now We've got a good break here and what you'll see is that after, you know Some of our pieces split off all over the place when I was getting little bits off It's split with a nice flat clean surface That's the property of cleavage where it splits along a particular plane Now we're going to take a look at rose quartz Now this is an example of a chunk of rose quartz We have and as I turn it you should be able to see that it's got sort of a very irregular Classy like but still a very irregular surface Now I'm not going to break this particular piece because I don't have very many samples of rose quartz But about a year ago one of my students accidentally smashed it and this was the results So you'll notice again each individual little piece is very rough and has very random uneven sides So this is an example of what happens when you break the mineral rose quartz So now we're going to look at a mineral called satin spar and Here's an example of satin spar Now as I move it you can kind of see that again It has a little bit of a glassy appearance and you can almost kind of see that it's got a little bit maybe of some lines Now I'm going to use my hammer here, and this one's not nearly as hard as my other one And I'm just going to break some chunks off the edge and you'll see that rather than breaking into random little chunks We get these very definite little lines here Now we'll look at muscovite and this here is a sample of muscovite now a lot of students will take a look at this and See this and see how thin it is and think that can't really be a rock But it is it's a particular mineral and it has a very interesting property here And I don't even necessarily have to use a hammer to break it But one can get in here this mineral will actually pull apart Into individual little sheets and that's the cleavage property of the mineral known as muscovite