6.6C: Minerals
Matter and Energy
Reading Science!
Name: __________________________________________
Date: _____________
Digging for Diamonds
Lexile 1190L
1
The Crater of Diamonds State Park in Pike
County, Arkansas is the only place in the world
where diamonds are produced that is open to
the public. The 37½ acre diamond-search area is
the eroded surface of a prehistoric volcanic pipe
that brought diamonds and a variety of semiprecious stones to the surface over 95 million
years ago. Today, visitors to this site can dig
through the plowed field in search of diamonds
and an assortment of other gem producing minerals, including amethyst,
peridot, quartz, and garnet.
2
Now, suppose your parents announced that this summer your family would
be taking a road trip and you’d be visiting the Crater of Diamonds State Park
as part of your annual family vacation. Upon hearing the news, you were
clearly excited—you’ve been sort of a “rockhound” for as long as you can
remember. After all, you never could resist picking up a rock that sparkled in
the light, and pretty-looking pebbles always seemed to catch your eye. This
would be the perfect opportunity to explore gemology and add to your
personal collection of gemstones!
3
Before the trip, you decide to provide your family with a bit of background
knowledge about gemology and gemstones. You let them know that
gemstones are minerals that have been carefully cut and polished, which
makes their surfaces smooth and shiny. People value gemstones because of
their beauty, rarity, and durability. They’re often used to create jewelry or
other decorative items. Traditionally, diamonds, rubies, emeralds, and
sapphires have been classified as precious stones due to their rarity,
hardness, and overall clarity. All other gemstones are considered
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R e a d i n g
S c i e n c e!
6.6C: Minerals
Matter and Energy
semi-precious because they’re more common and are softer. However,
you’re sure to inform your family to be on the lookout for some of the more
common semi-precious stones found at Crater of Diamonds. Lots of semiprecious stones are very popular and can be used to create beautiful jewelry.
4
As the big trip gets closer, everyone in your family is getting more excited
about visiting the Crater of Diamonds. You’ve decided, however, that the
time has come to share most important information with your family: how to
spot a diamond. After all, it’s important to determine whether they’ve
uncovered a diamond, or just a plain old rock. You share that there are
several physical properties are used to test and verify the identity of a
mineral: hardness, color, luster, and streak.
5
The property of hardness describes the strength of the forces holding atoms
together in a solid mineral. The Mohs scale is used to describe how easily a
mineral can be scratched, and has a range from 1-10. Diamonds are rated a
10 on the Mohs scale, meaning they’re the hardest minerals in the world. The
color of a mineral is often the most easily identifiable physical property.
Many minerals naturally occur in a wide range of colors. Diamonds are no
exception. They can be yellow, brown, blue, green, pink, orange, purple,
black, pink, red, or colorless. Colored diamonds contain impurities that cause
them to be different colors, while the colorless, transparent diamonds are
nearly pure. The property of luster refers to the way a mineral reflects the
light. Several different classifications of luster include metallic, dull, pearly,
and adamantine. Diamonds exhibit adamantine luster, which is seen in their
brilliant sparkle. The term streak refers to the color of the powder left by a
mineral. The streak of a mineral is commonly determined by scraping a
mineral along the non-glazed side of a porcelain tile. The color of the mark
left on the tile helps to identify the mineral. The streak of a diamond is white.
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R e a d i n g
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6.6C: Minerals
Matter and Energy
6
After explaining how a mineral’s physical properties can be tested and are
how they’re helpful in determining its identity, you’ll also explain that some
of these tests are better conducted in a laboratory setting. Now that your
family knows how physical properties are used to test the identity of
minerals, they’re even more excited to excavate some hidden gems. As the
countdown to vacation continues, you and your family are getting more and
more excited about the vacation to the Crater of Diamonds. Who knows
what treasures you’ll dig up!
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Reading Science!
6.6C: Minerals
Matter and Energy
1
2
3
Paragraph 5 of this passage mainly
tells about —
A
the physical properties of
minerals.
B
how to spot a diamond.
C
determining how rare a
diamond is.
D
how to test a diamond for value.
Complete the following analogy.
4
You can tell from reading this
passage that —
A
the narrator will definitely find a
diamond at the Crater of
Diamonds State Park.
B
diamonds are rare, valuable
gems.
C
garnet is as valuable as a
diamond.
D
semi-precious stones are ugly.
Complete the following analogy.
Mohs scale: hardness
Semi-precious: amethyst
A
Metallic: luster
A
Diamond: clear
B
Porcelain tile: streak
B
Rare: diamond
C
Cost: diamond purity
C
Precious: diamond
D
Colored diamond: clear
diamond
D
Diamond: adamantine
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Reading Science!
6.6C: Minerals
Matter and Energy
5
A Mohs scale is used to determine
________ of a mineral.
A
luster
B
hardness
C
monetary value
D
streak
5