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# Diamonds are almost impos- sible to detect directly

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Director
Joined: 26 Apr 2004
Posts: 941
Location: Taiwan
Diamonds are almost impos- sible to detect directly  [#permalink]

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28 Jan 2005, 06:06
Diamonds are almost impos-
sible to detect directly because they
are so rare: very rich kimberlite
Line pipes, the routes through which
(5) diamonds rise, may contain only
three carats of diamonds per ton
of kimberlite. Kimberlite begins as
magma in Earthâ€™s mantle (the layer
between the crust and the core). As
(10) 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
(15) diamond-stability field, where condi-
tions of pressure and temperature
are conducive to the formation of
diamonds. If diamonds are to sur-
vive, though, they must shoot toward
(20) Earthâ€™s surface quickly. Otherwise,
they revert to graphite or burn.
Explorers seeking diamonds look
for specks of â€œindicator mineralsâ€
Director
Joined: 26 Apr 2004
Posts: 941
Location: Taiwan

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28 Jan 2005, 06:07
please help me with passage.

OA will be given later.
Manager
Joined: 21 Jun 2004
Posts: 191

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28 Jan 2005, 08:46
1d
2e
3c ( a also looks probable to me)
4b
CEO
Joined: 15 Dec 2003
Posts: 3679

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01 Feb 2005, 07:43
Anybody wants to try this one?
_________________
Best Regards,

Paul
Manager
Joined: 19 Nov 2004
Posts: 229
Location: Germany

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01 Feb 2005, 08:18
1 - D

2 - A

3 - C

4 - C
SVP
Joined: 03 Jan 2005
Posts: 1702
Re: RC--diamond  [#permalink]

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01 Feb 2005, 09:23
1
(1)The primary purpose of the passage is to
A. discuss an objection to Gurneyâ€™s theories about the uses of indicator minerals
Definitely not
B. explore the formation of diamonds and the reasons for their scarcity
yes, but not the main purpose
C. analyze the importance of kimberlite pipes in the formation of diamonds
Again not the main purpose
D. define the characteristics of indicator minerals under differing conditions
Yes he did that, but still it's not the purpose
E. explain a method of determining whether kimberlite pipes are likely to contain diamonds
Yes

(2)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
This is mentioned for the ilmenites, instead of the garnet
B. commonness of occurrence
C. chemical signature
D. place of formation
E. appearance in conjunction with diamonds

(3)
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
No number is mentioned
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
Definitely out
E. the pipeâ€™s temperature was so high that it oxidized any diamonds the pipe might have contained
oxidization is not mentioned when talk about garnet

(4)
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.
Not helping
B. He found that since ilmenites do not form in the diamond-stability field, their presence indicates the absence of diamonds.
Not all ilmenites, but the ones with highly oxidized iron
C. He showed that highly oxidized iron content in ilmenites indicates a low survival rate for diamonds.
Thus this one is correct
D. He found that when the iron in ilmenites is highly oxidized, conditions in the magma were probably conducive to the formation of diamonds.
It's the opposite
E. He showed that ilmenites take on more or less oxygen in the kimberlite pipe depending on the concentration of diamonds.
What are you talking about
Director
Joined: 26 Apr 2004
Posts: 941
Location: Taiwan

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01 Feb 2005, 10:19
Thanks all , here is the OA

1, E

2, A

3, C

4, C

Congratulations, HongHu, it seems like you're ready for the test.
SVP
Joined: 03 Jan 2005
Posts: 1702

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01 Feb 2005, 10:24
Thank you! I haven't even prepared anything for RC and CR. Was counting on my basic skills.
CEO
Joined: 15 Dec 2003
Posts: 3679

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01 Feb 2005, 10:25
Hmmm, we have very differing answers here. This is one of those dreaded science passages The reason I took 1-B is because of the very first sentence which describes the tone of the passage.
Quote:
Diamonds are almost impos-
sible to detect directly because they
are so rare

One can spend years
Quote:
(30) 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
(35) are usually too sparse to mine

To me, (D) and (E) are more representative of the second half of the passage. Overall, we are talking about the scarcity of diamonds.

Chunjuwu, were there paragraphs in this passage? It would be good if they were separated into paragraphs accordingly.
_________________
Best Regards,

Paul
Director
Joined: 26 Apr 2004
Posts: 941
Location: Taiwan

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01 Feb 2005, 10:28
Thanks Paul.

Now I have is only pdf file.

If I have, I will share with you.
CEO
Joined: 15 Dec 2003
Posts: 3679

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01 Feb 2005, 10:29
wow, good job honghu, just realized I took too much time to go over the question before the answer got posted. Well, I am dumbfounded
_________________
Best Regards,

Paul
SVP
Joined: 03 Jan 2005
Posts: 1702

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01 Feb 2005, 10:34
But your grammar skills still PWNs everyone of us. (Yes you can see that I've been wandering around teh internet. ) And I can hardly get about half of the grammar questions right. So there. And we share our best tricks so we can collectively PWN the GMAT.
CEO
Joined: 15 Dec 2003
Posts: 3679

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01 Feb 2005, 11:01
Yup, I think RC was/is my downfall. If I take the GMAT again, I will know what to really focus on
_________________
Best Regards,

Paul
VP
Joined: 18 Nov 2004
Posts: 1154
Re: RC--diamond  [#permalink]

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01 Feb 2005, 12:03
HongHu wrote:
(1)The primary purpose of the passage is to
A. discuss an objection to Gurneyâ€™s theories about the uses of indicator minerals
Definitely not
B. explore the formation of diamonds and the reasons for their scarcity
yes, but not the main purpose
C. analyze the importance of kimberlite pipes in the formation of diamonds
Again not the main purpose
D. define the characteristics of indicator minerals under differing conditions
Yes he did that, but still it's not the purpose
E. explain a method of determining whether kimberlite pipes are likely to contain diamonds
Yes

(2)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
This is mentioned for the ilmenites, instead of the garnet
B. commonness of occurrence
C. chemical signature
D. place of formation
E. appearance in conjunction with diamonds

(3)
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
No number is mentioned
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
Definitely out
E. the pipeâ€™s temperature was so high that it oxidized any diamonds the pipe might have contained
oxidization is not mentioned when talk about garnet

(4)
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.
Not helping
B. He found that since ilmenites do not form in the diamond-stability field, their presence indicates the absence of diamonds.
Not all ilmenites, but the ones with highly oxidized iron
C. He showed that highly oxidized iron content in ilmenites indicates a low survival rate for diamonds.
Thus this one is correct
D. He found that when the iron in ilmenites is highly oxidized, conditions in the magma were probably conducive to the formation of diamonds.
It's the opposite
E. He showed that ilmenites take on more or less oxygen in the kimberlite pipe depending on the concentration of diamonds.
What are you talking about

I got C, E, C, C......Honghu, for ques 2 where in the passage "E" is mentioned abt differences in garnet ??

Also for ques 1....seems like only latter half of the passage mentions a method of determining whether kimberlite pipes are likely to contain diamonds.....I am not convinced that this is the main idea of the passage. Doesn't seem like author set out to write this passage to mention a method only, thoughts ?.....
SVP
Joined: 03 Jan 2005
Posts: 1702
Re: RC--diamond  [#permalink]

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01 Feb 2005, 12:20
banerjeea_98 wrote:
I got C, E, C, C......Honghu, for ques 2 where in the passage "E" is mentioned abt differences in garnet ??

"G10 garnets, a type of garnet typically found in diamond-rich pipes"
Meaning garnets appear in conjunction with diamonds.

Quote:
Also for ques 1....seems like only latter half of the passage mentions a method of determining whether kimberlite pipes are likely to contain diamonds.....I am not convinced that this is the main idea of the passage. Doesn't seem like author set out to write this passage to mention a method only, thoughts ?.....

Hmm I don't know how to talk about this. Basically we can shorten the paragraph like this:

Diamonds are very important. Because of the way they are formed we can use some other things to locate diamonds. But it is still hard to locate them. This person, however, discovered a couple neat ways so that it isn't so hard to find diamonds now.

So what is the purpose of this paragraph? It talks about diamonds, yes, but not everything about diamond. It's about how to find them. And more specifically, the method that makes it easy to find them.
VP
Joined: 18 Nov 2004
Posts: 1154
Re: RC--diamond  [#permalink]

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01 Feb 2005, 12:32
HongHu wrote:
banerjeea_98 wrote:
I got C, E, C, C......Honghu, for ques 2 where in the passage "E" is mentioned abt differences in garnet ??

"G10 garnets, a type of garnet typically found in diamond-rich pipes"
Meaning garnets appear in conjunction with diamonds.

Quote:
Also for ques 1....seems like only latter half of the passage mentions a method of determining whether kimberlite pipes are likely to contain diamonds.....I am not convinced that this is the main idea of the passage. Doesn't seem like author set out to write this passage to mention a method only, thoughts ?.....

Hmm I don't know how to talk about this. Basically we can shorten the paragraph like this:

Diamonds are very important. Because of the way they are formed we can use some other things to locate diamonds. But it is still hard to locate them. This person, however, discovered a couple neat ways so that it isn't so hard to find diamonds now.

So what is the purpose of this paragraph? It talks about diamonds, yes, but not everything about diamond. It's about how to find them. And more specifically, the method that makes it easy to find them.

I see why I was wrong in ques 2...I thot "appearance in conjunction of diamond" meant garnets that have a look and feel of diamonds....didn't understand the sentence atall. But I am still not convinced that the main idea is to explain one method to find diamonds
Manager
Joined: 03 May 2015
Posts: 61
Re: Diamonds are almost impos- sible to detect directly  [#permalink]

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23 Jul 2015, 17:03
chunjuwu wrote:
Diamonds are almost impos-
sible to detect directly because they
are so rare: very rich kimberlite
Line pipes, the routes through which
(5) diamonds rise, may contain only
three carats of diamonds per ton
of kimberlite. Kimberlite begins as
magma in Earthâ€™s mantle (the layer
between the crust and the core). As
(10) 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
(15) diamond-stability field, where condi-
tions of pressure and temperature
are conducive to the formation of
diamonds. If diamonds are to sur-
vive, though, they must shoot toward
(20) Earthâ€™s surface quickly. Otherwise,
they revert to graphite or burn.
Explorers seeking diamonds look
for specks of â€œindicator mineralsâ€

why do ppl post such passages without questions?
Intern
Joined: 16 Dec 2013
Posts: 32
Location: United States
GPA: 3.7
Re: Diamonds are almost impos- sible to detect directly  [#permalink]

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28 Jul 2015, 14:41
sagarbuss wrote:
chunjuwu wrote:
Diamonds are almost impos-
sible to detect directly because they
are so rare: very rich kimberlite
Line pipes, the routes through which
(5) diamonds rise, may contain only
three carats of diamonds per ton
of kimberlite. Kimberlite begins as
magma in Earthâ€™s mantle (the layer
between the crust and the core). As
(10) 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
(15) diamond-stability field, where condi-
tions of pressure and temperature
are conducive to the formation of
diamonds. If diamonds are to sur-
vive, though, they must shoot toward
(20) Earthâ€™s surface quickly. Otherwise,
they revert to graphite or burn.
Explorers seeking diamonds look
for specks of â€œindicator mineralsâ€

Incomplete passage...request the moderator to remove
Director
Joined: 26 Oct 2016
Posts: 606
Location: United States
Concentration: Marketing, International Business
Schools: HBS '19
GMAT 1: 770 Q51 V44
GPA: 4
WE: Education (Education)
Re: Diamonds are almost impos- sible to detect directly  [#permalink]

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29 Jun 2017, 22:54
1
1)Diamonds are almost impossible to detect directly because they are so rare:
very rich kimberlite Line pipes, the routes through which (5) diamonds rise, may contain only three carats of diamonds per ton
of kimberlite. – (EXPLAINS THE FIRST LINE (NOTICE THE COLON AFTER THE LINE)
Introductory lines emphasize on kimberlite and inform that these pipes may contain only a small percentage of diamond. Rest of the passage expand on this-
Kimberlite begins as magma in Earthâ€™s mantle (the layer between the crust and the core). As (10) 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 (15) diamond-stability field, where conditions of pressure and temperature are conducive to the formation of diamonds.- (EXPLAINS THE KIMBERLITE PROCESS). If diamonds are to survive, though, they must shoot toward
(20) Earthâ€™s surface quickly. Otherwise, they revert to graphite or burn. Explorers seeking diamonds look for specks of â€œindicator mineralsâ€
peculiar to the mantle but carried up.....The entire passage focus on the kimberlite pipes and how likely they are to contain diamonds. Formation of diamond and their scarcity is also explained in regard of Kimberlite only and hence E becomes the primary purpose.
2)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 - Correct, used to describe properties of ilmenites
B. commonness of occurrence - Incorrect, a type of garnet typically found in diamond-rich pipes
C. chemical signature - Incorrect, are lower in calcium and higher in chrome than garnets from barren pipes.
D. place of formation - Incorrect, Geochemists John Gurney showed that garnets with this composition were formed only in the diamond-stability field
E. appearance in conjunction with diamonds - Incorrect, a type of garnet typically found in diamond-rich pipes
3)The word "suggests" indicates that this is an Inference question, so we'll need to
1) re-read the pertinent info in the passage and try to make a prediction, and
2) select the answer choice that is closest to the tiny details from the passage.
Where is "presence of G10 garnet in a kimberlite pipe" mentioned?
I see it in the second paragraph: ...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.
So, what does LOW calcium/HIGH chrome indicate? Probably a profitable pipe!
Prediction: \$\$\$. The correct answer is (C).
4)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. Correct, When iron became highly oxidized, so did diamonds; that is, they vaporized into carbon dioxide.
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.
_________________
Thanks & Regards,
Anaira Mitch
Re: Diamonds are almost impos- sible to detect directly   [#permalink] 29 Jun 2017, 22:54
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# Diamonds are almost impos- sible to detect directly

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