Hand Specimen Description

Question 1

Melanocratic

Answer 1

Mostly dark grains

Question 2

Leucocratic

Answer 2

Mostly light grained

Question 3

Mesocratic

Answer 3

Mostly intermediate lightness grains

Question 4

Mafic

Answer 4

MAgnesium, FerrIC

Dark minerals

Question 5

Felsic

Answer 5

FELdspar, SIliCates

Light minerals

Question 6

3 properties for colour

Answer 6

1) Lightness (Melanocratic, Mesocratic, Leucocratic)
2) Index (Mafic/Felsic)
3) Hue

Question 7

Phaneritic

Answer 7

Can see individual minerals

Question 8

Aphaneritic

Answer 8

Can’t distinguish individual minerals

Question 9

Crystals over 5mm

Answer 9

Coarse-grained

Question 10

Crystals 2-5mm

Answer 10

Medium-sized

Question 11

Crystals less than 2mm

Answer 11

Fine-grained

Question 12

Cryptocrystalline

Answer 12

If you can’t see individual crystals with a hand lens

Cryptocrystalline is a rock texture made up of such minute crystals that its crystalline nature is only vaguely revealed even microscopically

Question 13

Equigranular

Answer 13

Equal sized grains

Question 14

Interlocking crystals indicate

Answer 14

Igneous (or metamorphic)

Question 15

Interlocking crystals indicate

Answer 15

Igneous (or metamorphic)

Question 16

Granular rocks indicate

Answer 16

Sedimentary

Question 17

Groundmass

Answer 17

Finer minerals around phenocrysts

Question 18

Foliation

Answer 18

Foliation in geology refers to repetitive layering in metamorphic rocks.

Question 19

Schistosity

Answer 19

The foliation in schist or other coarse-grained, crystalline rock due to the parallel, planar arrangement of mineral grains of the platy, prismatic, or ellipsoidal types, usually mica. It is considered by some to be a type of cleavage.

Question 20

Bedding

Answer 20

Beds are the layers of sedimentary rocks that are distinctly different from overlying and underlying subsequent beds of different sedimentary rocks.

Question 21

Strata or Stratum

Answer 21

In geology and related fields, a stratum is a layer of sedimentary rock or soil, or igneous rock that was formed at the Earth’s surface

Question 22

Lamination

Answer 22

lamination is a small-scale sequence of fine layers (laminae; singular: lamina) that occurs in sedimentary rocks. Laminae are normally smaller and less pronounced than bedding

Question 23

Friable

Answer 23

rock or mineral that crumbles naturally or is easily broken, pulverized, or reduced to powder, such as a soft and poorly cemented sandstone.

Question 24

Vesiculation and Vesicles

Answer 24

Vesicles are the small holes left behind after lava cools and turns into volcanic rock. Vesicles help geologists understand the cooling history of extrusive (volcanic rocks) because lava contains large amounts of dissolved gases that are released as the lava hardens.

Question 25

Frothy

Answer 25

If so many bubbles are escaping from lava that it ends up containing more bubble holes than solid rock, the resulting texture is said to be frothy. Pumice is the name of a type of volcanic rock with a frothy texture.

Question 26

Hardness scale

Answer 26

Mohs scale

Question 27

Diaphaneity

Answer 27

Transparency

Question 28

11 properties used 3 Shape/Form 4 Visual 4 Physical

Answer 28

``` Shape - Crystal Form - Shape (Habit) - Crystal System Visual - Colour - Diaphaneity - Streak - Lustre Physical - Hardness - Cleavage - Fracture - Specific Gravity ```