 Hi I'm Maureen Feynman. I'm Heather McHugh Brun. And the topic of this week's unit is garnet. So garnet is a silicate mineral that grows at high pressures most commonly in the interior of the earth. Garnet is most commonly found in metamorphic rocks which are a little less common at the surface of the earth than some of the other types of rocks and minerals that we've been looking at so far. Silic the garnet is a very hard mineral. It has a hardness depending on the specific chemical composition of between six and a half and eight on a Mohs scale. And that has a couple of implications for the use of garnet. One is that garnet is relatively difficult to break or cut although it can still be broken into chips or carved carefully into shapes. Another result of the hardness of garnet is that it's really useful not only as a material in art but also as a material for producing art. Hard garnet will form an abrasive that can be used for sanding grinding polishing and it can also be used to make tools for cutting other less hard minerals or rocks. In art what we're going to be seeing in this particular set of lessons is that garnet is used primarily in jewelry production and it really becomes available sort of in the late classical period when Alexander the Great and his armies pushed into the Indian subcontinent extending the territory of Greece and well well into the the eastern world and this opened up trade routes for garnets and suddenly shortly after Alexander's campaigns we start to see the emergence of all of these incredible garnets in jewelry and that's something that's going to be addressed by one of our short video clips with Adam Levine from the Toledo Museum of Art. He presents a number of objects to us and we'll sort of trace the the ways in which these garnets were used in art and the symbolism people tended to really favor the red garnets and even though these all look sort of black to you here we're going to insert an image so that you can see that under light and when cut into thin sections these actually shine sort of a deep blood red and this could be used in the medieval period for example as a symbol for blood.