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Colored Stones Exam > GIA Colored Stones Exam 601-650 > Flashcards

GIA Colored Stones Exam 601-650 Flashcards

1
Q

A deposit where gems are found in the rock that carried them to the earth’s surface is called __________.

A

a primary deposit

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2
Q

A deposit where gems eroded from the source rock and remained in place nearby is called an __________.

A

eluvial deposit

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3
Q

What is a workable alluvial deposit of gem minerals with economic potential called?

A

a placer

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4
Q

Kunzite is most often found in association with what?

A

tourmaline and beryl in pegmatite

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5
Q

Mynamar’s famous Mogok ruby deposits were formed by ___________.

A

regional metamorphism

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6
Q

Pegmatite gems are rich in volatile elements like _________; __________; and __________.

A

beryllium; boron and lithium

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7
Q

Most of the gems in Tanzania’s Umba River Valley are found in what type of deposits?

A

placer

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8
Q

Emerads are rarely found in placer deposits because they’re __________.

A

too soft

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9
Q

A deposit where gems are eroded from their source rock; then transported away from the source and further concentrated.

A

alluvial

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10
Q

Localized changes caused by an igneous intrusion that takes place where the magma meets the surrounding rock. New minerals may form due to temperature changes or introduction of fluids from the magma.

A

contact metamorphism

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11
Q

The earth’s innermost layer is called the ________.

A

mantle

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12
Q

The surface and outermost layer of the earth is called the _______.

A

crust

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13
Q

Rock formed by the crystallization of molten material.

A

igneous rock

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14
Q

A large mass of igneous rock that crystallizes underground without reaching the surface is called an __________.

A

intrusion

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15
Q

A general term for molten rock.

A

magma

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16
Q

The layer between the earth’s crust and its core is called the _____________.

A

mantle

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17
Q

The circulation in the mantle that drives the movement of the earth’s plates is called ____________.

A

mantle convection

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18
Q

Rock altered by heat and pressure; or by heated fluids from magma is called a ____________.

A

metamorphic rock

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19
Q

An igneous rock formed by cooling; once_molten granite that follows fractures in its surrounding rock. It may contain very large drystalsm and its shape is often thin and contorted is called _____________.

A

pegmatite

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20
Q

A section of the earth’s rigid outer crust is called a __________.

A

plate

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21
Q

The study of the formation; structure; and movement of the plates of the earth’s crust is called ___________.

A

plate tectonics

22
Q

Crystallization of minerals from a gas is called __________.

A

pneumatolysis

23
Q

Gems found in the rock that carried them to the surface are found in this deposit.

A

primary

24
Q

Changes in rock type and minerals over a wide area caused by heat and pressure of large_scale geological events is called _____________.

A

regional metamorphism

25
Q

A constant formation and recycling process that creates new rock from old is called the ___________.

A

rock cycle

26
Q

Gems found away from their primary source are called ___________.

A

secondary deposit

27
Q

Rock produced from the eroded and weathered remains of existing rocks are called ____________.

A

sedimentary

28
Q

A process that occurs when two of the earth’s plates collide; forcing one under the other is called ____________.

A

subduction

29
Q

A mineral deposit that occupies an existing fissure or fracture in the rock is called a ___________.

A

vein

30
Q

Pertaining to igneous activity at the earth’s surface; where magma erupts through a volcano or a fissure is called ________.

A

volcanic

31
Q

A “foreign crystal” that formed in unrelated tocks and was brought to the surface as a passenger in magma is called a ____________.

A

xenocryst

32
Q

Geological conditions during ___________ ___________ are favorable for gem formation.

A

mountain building

33
Q

Igneous rocks; large crystals indicate slow cooling; while small crystals indicate _____________.

A

quick cooling

34
Q

A majority of the largest and most perfect gem crystals come from _________.

A

pegmatites

35
Q

What can transfer minerals in solution and redeposit them in veins to form gems?

A

superheated; pressurized water

36
Q

Written information on dyeing gems dates back to about what year?

A

200BC

37
Q

Heat can lighten amethyst’s purple by _________.

A

causing changes in color centers

38
Q

Creating asterism with heat treatment is most common in what gemstone?

A

synthetic corundum

39
Q

What coloring agents do treaters use during lattice diffusion to create a shallow layer of blue color in corundum?

A

titanium oxide and iron oxide

40
Q

How deep is the color layer that lattice diffusion with titanium or chromium creates in corundum?

A

0.01mm to 0.50mm

41
Q

What agent can create a shallow layer of asterism when it’s introduced below the surface of a corundum cabochon by lattice diffusion?

A

titanium oxide

42
Q

For effective clarity enhancement; the material used to fill a gem’s fractures must have nearly the same?

A

refractive index as the gem

43
Q

After irradiation; which gem’s color is stable under normal wearing conditions?

A

orange sapphire

44
Q

What treatment is often used with jadeite?

A

bleached and polymer impregnated

45
Q

The Zachery method is a treatment that is applied to what gemstone?

A

turquoise

46
Q

Quartz or topaz with a thin layer of gold deposited on the surface is known as ___________.

A

aqua aura

47
Q

Heat treatment in a reducing environment does what to sapphire?

A

deepens the blue color

48
Q

Treaters use “sugar treatment” to enhance what gemstone?

A

opal

49
Q

A treatment in which a gem is exposed to high temperatures and chemicals to allow penetration of color_causing elements is called ____________.

A

lattice diffusion

50
Q

An oxygen poor environment that surrounds a gem during heat treatment; causing it to lose oxygen is called a __________.

A

reducing environment

Colored Stones Exam (15 decks)

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