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 托福聽力考古題 geolgy lecture - feldspars  

Woman :

I'd like to begin by thanking Dr. Kane for inviting me to be here today. Although I'm not a geologist, I have been collecting minerals for years. My collection is rally diverse because I've traveled all over the world to find them. Today I've brought a few specimens for you to see. After I discuss each one, I'll pass it around so that you can look at it more closely.  

As you know, feldspars are the most abundant minerals and are divided into a number of types. These first samples are orthoclases. Notice that they vary in color from white to pink to red. This glassy one is found in volcanic rock --- in fact, I found it in New Mexico on a collecting trip.  

This next sample that I'll pass around is a microcline mineral --- also called amazonstone. You can identify it by its bright green color. It's often used in jewelry and really is quite attractive.  

These final samples are all plagioclase feldspars. Many plagioclases are very rare, so I'm particularly proud of the variety in my collection.  

I've also brought a few slides of some large mineral samples, and if you'll turn out the light now, I'd like to show them to you.