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Diamonds are almost impossible to detect directly because

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Re: Diamonds are almost impossible to detect directly because  [#permalink]

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New post 19 Sep 2016, 05:41
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In question 3, I was doubting between options B and C.

The passage suggests that the presence of G10 garnet in a kimberlite pipe indicates that:

B) the levels of calcium and chrome in the pipe are conducive to diamond formation
I discarded this option because the levels of calcium and chrome do not lead to diamond formation. They are rather a signal of diamond formation.

C) the pipe passed through a diamond-stability field and thus may contain diamonds
Support for this option:
"For example, G10 garnets, a type of garnet typically found in diamond-rich pipes, are lower in calcium and higher in chrome than garnets from barren pipes. Geochemists John Gurney showed that
garnets with this composition were formed only in the diamond-stability field;..."

Could you please give your opinion on my reasoning for discarding option B?
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New post 01 May 2017, 00:16
Nice small passage to practise...
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Re: GMAT Prep RC: Diamonds are almost impossible to detect  [#permalink]

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New post 04 Jun 2017, 18:46
Took me 10 mins 40 seconds overall. All correct !
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Re: GMAT Prep RC: Diamonds are almost impossible to detect  [#permalink]

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New post 04 Jul 2017, 23:55
Took 6 mins 31 secs , 1 wrong
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New post 04 Oct 2017, 01:41
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Hey GMATNinja and GMATNinjaTwo

can you help to explain the below question? I am not convinced with the answers given in this thread

Each of the following is mentioned in the passage as a difference between G10 garnet and other versions of garnet EXCEPT
(A)level of oxidation
(B)commonness of occurrence
(C)chemical signature
(D)place of formation
(E)appearance in conjunction with diamond
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GMAT Prep RC: Diamonds are almost impossible to detect  [#permalink]

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New post 06 Nov 2017, 12:00
Took me 8 mins to complete.

Got 1 wrong.
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New post 28 Dec 2017, 03:59
roopika2990 wrote:
Diamonds are almost impossible to detect directly because they are so rare: very rich kimberlite pipes, the routes through which diamonds rise, may contain only three carats of diamonds per ton of kimberlite. Kimberlite begins as magma in Earth’s mantle (the layer between the crust and the core). As the magma smashes through layers of rock, it rips out debris, creating a mix of liquid and solid material. Some of the solid material it brings up may come from a so-called diamond-stability field, where conditions of pressure and temperature are conducive to the formation of diamonds. If diamonds are to survive, though, they must shoot toward Earth’s surface quickly. Otherwise, they revert to graphite or burn. Explorers seeking diamonds look for specks of “indicator minerals” peculiar to the mantle but carried up in greater quantities than diamonds and eroded out of kimberlite pipes into the surrounding land. The standard ones are garnets, chromites, and ilmenites. One can spend years searching for indicators and tracing them back to the pipes that are their source; however, 90 percent of kimberlite pipes found this way are barren of diamonds, and the rest are usually too sparse to mine.

In the 1970’s the process of locating profitable pipes was refined by focusing on the subtle differences between the chemical signatures of indicator minerals found in diamond-rich pipes as opposed to those found in barren pipes. For example, G10 garnets, a type of garnet typically found in diamond-rich pipes, are lower in calcium and higher in chrome than garnets from barren pipes. Geochemists John Gurney showed that garnets with this composition were formed only in the diamond-stability field; more commonly found versions came from elsewhere in the mantle. Gurney also found that though ilmenites did not form in the diamond-stability field, there was a link useful for prospectors: when the iron in ilmenite was highly oxidized, its source pipe rarely contained any diamonds. He reasoned that iron took on more or less oxygen in response to conditions in the kimberlitic magma itself—mainly in response to heat and the available oxygen. When iron became highly oxidized, so did diamonds; that is, they vaporized into carbon dioxide.
The primary purpose of the passage is to
(A)discuss an objection to Gurney's theories about the uses of indicator minerals
(B)explore the formation of diamonds and the reasons for their scarcity
(C)analyze the importance of kimberlite pipes in the formation of diamonds
(D)define the characteristics of indicator minerals under differing conditions
(E)explain a method of determining whether kimberlite pipes are likely to contain diamonds



Each of the following is mentioned in the passage as a difference between G10 garnet and other versions of garnet EXCEPT
(A)level of oxidation
(B)commonness of occurrence
(C)chemical signature
(D)place of formation
(E)appearance in conjunction with diamond



The passage suggests that the presence of G10 garnet in a kimberlite pipe indicates that
(A)the pipe in which the garnet is found has a 90% chance of containing diamonds
(B)the levels of calcium and chrome in the pipe are conducive to diamond formation
(C)the pipe passed through a diamond-stability field and thus may contain diamonds
(D)any diamonds the pipe contains would not have come from the diamond-stability field
(E)the pipe's temperature was so high that it oxidized any diamonds the pipe might have contained



According to the passage, Gurney refined the use of ilmenites in prospecting for diamonds in which of the following ways?
(A)He found that ilmenites are brought up from the mantle by kimberlite pipes and erode out into the surrounding land in greater quantities than diamonds.
(B)He found that since ilmenites do not form in the diamond-stability field, their presence indicates the absence of diamonds.
(C)He showed that highly oxidized iron content in ilmenites indicates a low survival rate for diamonds.
(D)He found that when the iron in ilmenites is highly oxidized, conditions in the magma were probably conducive to the formation of diamonds.
(E)He showed that ilmenites take on more or less oxygen in the kimberlite pipe depending on the concentration of diamonds





Hi,

mikemcgarry, chetan2u, VeritasPrepKarishma, GMATNinja, sayantanc2k

Can you please help with the below question:

Each of the following is mentioned in the passage as a difference between G10 garnet and other versions of garnet EXCEPT
(A)level of oxidation
(B)commonness of occurrence
(C)chemical signature
(D)place of formation
(E)appearance in conjunction with diamond

Can you help me identify the evidence from the passage to rule out option E ?

Thanks in advance :-)
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New post 28 Dec 2017, 06:09
Poorvasha wrote:
roopika2990 wrote:

In the 1970’s the process of locating profitable pipes was refined by focusing on the subtle differences between the chemical signatures of indicator minerals found in diamond-rich pipes as opposed to those found in barren pipes. For example, G10 garnets, a type of garnet typically found in diamond-rich pipes, are lower in calcium and higher in chrome than garnets from barren pipes. Geochemists John Gurney showed that garnets with this composition were formed only in the diamond-stability field; more commonly found versions came from elsewhere in the mantle. Gurney also found that though ilmenites did not form in the diamond-stability field, there was a link useful for prospectors: when the iron in ilmenite was highly oxidized, its source pipe rarely contained any diamonds. He reasoned that iron took on more or less oxygen in response to conditions in the kimberlitic magma itself—mainly in response to heat and the available oxygen. When iron became highly oxidized, so did diamonds; that is, they vaporized into carbon dioxide.



Hi,

mikemcgarry, chetan2u, VeritasPrepKarishma, GMATNinja, sayantanc2k

Can you please help with the below question:

Each of the following is mentioned in the passage as a difference between G10 garnet and other versions of garnet EXCEPT
(A)level of oxidation
(B)commonness of occurrence
(C)chemical signature
(D)place of formation
(E)appearance in conjunction with diamond

Can you help me identify the evidence from the passage to rule out option E ?

Thanks in advance :-)


HI...

it is given in the coloured portion above that G10 are found in diamond rich pipe whereas the other garnet in barren pipe..
so G10 appears in conjunction with diamond..

choice E means G10 appearing along with diamond.
May be one can get confused in literal meaning of APPEARANCE as LOOKS
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New post 28 Dec 2017, 13:53
chetan2u wrote:
Poorvasha wrote:
roopika2990 wrote:

In the 1970’s the process of locating profitable pipes was refined by focusing on the subtle differences between the chemical signatures of indicator minerals found in diamond-rich pipes as opposed to those found in barren pipes. For example, G10 garnets, a type of garnet typically found in diamond-rich pipes, are lower in calcium and higher in chrome than garnets from barren pipes. Geochemists John Gurney showed that garnets with this composition were formed only in the diamond-stability field; more commonly found versions came from elsewhere in the mantle. Gurney also found that though ilmenites did not form in the diamond-stability field, there was a link useful for prospectors: when the iron in ilmenite was highly oxidized, its source pipe rarely contained any diamonds. He reasoned that iron took on more or less oxygen in response to conditions in the kimberlitic magma itself—mainly in response to heat and the available oxygen. When iron became highly oxidized, so did diamonds; that is, they vaporized into carbon dioxide.



Hi,

mikemcgarry, chetan2u, VeritasPrepKarishma, GMATNinja, sayantanc2k

Can you please help with the below question:

Each of the following is mentioned in the passage as a difference between G10 garnet and other versions of garnet EXCEPT
(A)level of oxidation
(B)commonness of occurrence
(C)chemical signature
(D)place of formation
(E)appearance in conjunction with diamond

Can you help me identify the evidence from the passage to rule out option E ?

Thanks in advance :-)


HI...

it is given in the coloured portion above that G10 are found in diamond rich pipe whereas the other garnet in barren pipe..
so G10 appears in conjunction with diamond..

choice E means G10 appearing along with diamond.
May be one can get confused in literal meaning of APPEARANCE as LOOKS



Thanks for the explanation chetan2u :-)
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New post 07 Jun 2018, 10:14
I am usually good with RCs but this one killed me. I am never going to a diamond store again.
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New post 07 Jun 2018, 21:46
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New post 19 Jun 2018, 00:43
Nice passage. Made a careless error in the first question. Rest all were correct
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New post 23 Dec 2018, 23:52
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Dear Moderators workout, u1983 broall Gnpth

Please add the below question
Source: Practice Exam 4 (mba.com)

Q. Which of the following best describes the primary purpose of the second paragraph of the passage?

(A)It describes a method of diamond formation different from the one described in the first paragraph.
(B)It gives examples of the ways in which a method for locating diamonds may be applied to other gems.
(C)It gives examples of exceptions to the natural phenomenon of diamond formation as described in the first paragraph.
(D)It discusses an improvement to the process of diamond prospecting described in the first paragraph.
(E)It challenges the scientific foundation of the method of diamond prospecting described in the first paragraph.

OA is D, would appreciate if explanation is also provided
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New post 23 Dec 2018, 23:54
Dear souvik101990 Skywalker18

Please add the below question
Source: Practice Exam 4 (mba.com)

Q. Which of the following best describes the primary purpose of the second paragraph of the passage?

(A)It describes a method of diamond formation different from the one described in the first paragraph.
(B)It gives examples of the ways in which a method for locating diamonds may be applied to other gems.
(C)It gives examples of exceptions to the natural phenomenon of diamond formation as described in the first paragraph.
(D)It discusses an improvement to the process of diamond prospecting described in the first paragraph.
(E)It challenges the scientific foundation of the method of diamond prospecting described in the first paragraph.

OA is D, would appreciate if explanation is also provided
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New post 24 Dec 2018, 01:20
deddex wrote:
Dear Moderators workout, u1983 broall Gnpth

Please add the below question
Source: Practice Exam 4 (mba.com)

Q. Which of the following best describes the primary purpose of the second paragraph of the passage?

(A)It describes a method of diamond formation different from the one described in the first paragraph.
(B)It gives examples of the ways in which a method for locating diamonds may be applied to other gems.
(C)It gives examples of exceptions to the natural phenomenon of diamond formation as described in the first paragraph.
(D)It discusses an improvement to the process of diamond prospecting described in the first paragraph.
(E)It challenges the scientific foundation of the method of diamond prospecting described in the first paragraph.

OA is D, would appreciate if explanation is also provided


Thank you deddex I see someone has added it already. Isn't the explanation provided on the practice exam?
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New post 05 Mar 2019, 02:10
For Q1: Primary Purpose-

E. explain a method of determining whether kimberlite pipes are likely to contain diamonds … the entire idea of writing out the passage revolves around bringing to light that one recent method that has made things a lot easier on part of those in search of diamond … perfect match … CORRECT
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Re: Diamonds are almost impossible to detect directly because   [#permalink] 05 Mar 2019, 02:10

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