问题 问答题 简答题

试结合矿物的标本,阐述表观鉴别常见矿物的基本方法及几种主要矿物的特征。

答案

参考答案:

鉴别方法:用显微镜观察法、化学分析法、专用仪器分析法、表观鉴别法。一般先观察结晶形态,然后确定光学性质和力学性质的特征及其他特征,综合起来,作出判断,确定矿物的类别,在鉴别时,应事先找出矿物的新鲜表面,才能得到正确的结果,风化岩石中的矿物不能反映真正矿物的特征。

主要特征:

黄铁矿:形状立方体或块粒状,颜色铜黄色,条痕绿黑,光泽金属,硬度5~6,无解理。

赤铁矿、石英:形状为块状、柱状,颜色红褐色、乳白色或无色,条痕樱红或无光泽半金属、玻璃、油脂,硬度5~7,无解理。

方解石、白云石和石膏:菱形、粒状、块状、菱状、板状、纤维,条痕无或白,光泽玻璃或丝绢,硬度2~4,解理三组完全或中等。

阅读理解

The website “FarmersOnly.com” calls itself an online dating and friendship finder. The idea started in the mind of a man, Jerry Miller in Ohio. He wondered how farmers could meet new people who understand the life of a farmer. Jerry Miller is not a farmer but he represents a lot of farmers.

As he tells it, the idea for the site was planted when a farmer told him one day that she was recently divorced and would like to date. But someone would invite her to meet for coffee at nine o’clock at night, when she had to start her day at five the next morning.

So, in 2005, Jerry Miller launched his website. “You don’t have to be a farmer to be on FarmersOnly.com, but you do have to have the good old-fashioned traditional values of America’s Heartland.” 

You also have to live in the United States or Canada to be a member of the site. Some services are free, but a full membership costs fifty dollars for a year. As of last week the site listed more than 58,000 members. Many of them are farmers in the United States. Others are students or workers involved in some way with agriculture. Jerry Miller tells us about thirty marriages in the last year have resulted from his website.

Some farmers have also found love through a group, Singles in Agriculture, which was formed as a nonprofit organization in 1986. It organizes gatherings that usually end with a dance, but is not a dating service. The purpose is to support educational and social activities that offer people a chance for friendship. Its website, singlesinag.org, says there are more than 1,000 members across the nation and as far away as France.

小题1:Jerry Miller started singlesinag.org in order to     .

A.help farmers

B.represent farmers

C.support traditions

D.understand farmers小题2:Which of the following is true of singlesinag.org?

A.It provides dating services.

B.Only farmers can become its members.

C.Its services are free.

D.Farmers in France can’t benefit from it.小题3: The author of the text intends to     .

A.advertise for the two websites

B.urge readers to help farmers

C.intro duce two websites

D.encourage social activities小题4:It can be inferred from the text that     .

A.farmers are easy to meet new people

B.the Internet helps improve farmers’ social life

C.all farmers desire marriage

D.more farmers get divorced in the USA

多项选择题