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with examples,explain the useful and limitation of colour and streak as criteria in mineral identification.

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asked May 1 by O'martha (120 points)

1 Answer

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Identifying rocks is a challenging endeavor at best. A simple example is silicon dioxide. You can go down the list of silicate rocks and you have chert, flint, agate, chalcedony, quartz, citrine, amethyst and many more and they are all chemically mostly silicon dioxide. And, differences in how they formed, pressure, temperature, trace elements all go in to forming those rocks. They are all SiO2. They all streak test white. So there is one limitation. That is why using multiple tests is the best way. Backlight a specimen to see if it is translucent. Does light pass through it? Specific density. Magnetic, or not magnetic. Reacts to acid, does not react to acid. Streak test results are all pieces of information which will help you rule out some things. When used collectively, they give you the best chance to accurately identify a sample.

Here is a short article about streak test.

http://www.minerals.net/resource/property/Streak.aspx

answered May 4 by Weasel (55,650 points)
 


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