Ore Morphology and Textures

Question 1

Regular Deposits

Answer 1

Beds

Veins

Question 2

Irregular Deposits

Answer 2

Stocks

Replacement

Question 3

layers/beds parallel to bedding or magmatic layering

Answer 3

Bed-Stratiform Deposits

Question 4

zones parallel or sub-parallel to bedding or schistosity

Answer 4

Bed-Stratabound

Question 5

formed by deposition along faults or fractures

Answer 5

Vein

Question 6

wide at the center and tapered at the sides

Answer 6

Lens

Question 7

cylindrical or tube-shaped enrichment zones with oval cross-sections

Answer 7

Pipes or mantos

Question 8

develop along intersection zones of faults or dikes

Answer 8

Pipes or Mantos

Question 9

ore occurrence that can be followed along a strike

Answer 9

Regular Deposits

Question 10

no geometric shape

variable and abruptly changing boundaries

Answer 10

Stocks

Question 11

ore with no geometric shape and variable directions and dimensions

Answer 11

Irregular Deposits

Question 12

ore minerals are found along cross-cutting veinlets

Answer 12

Stockwork

Question 13

ore minerals are scattered as individual or small clusters of inclusions

Answer 13

Dissemination

Question 14

ore minerals are disseminated in the matrix

Answer 14

Breccia

Question 15

ores which have undergone deformation following its formation, giving riseto brecciation of rock as well as minerals

Answer 15

Brecciated texture

Question 16

broken rock fragments

Answer 16

Clasts

Question 17

fill spaces between clasts

Answer 17

Matrix

Question 18

Importance of studying ore textures

Answer 18

1. Determine time relationships of mineral assemblages
2. Environment of Formation
3. Manner of Deposition

Question 19

Categories of Ore textures

Answer 19

Magmatic Deposition
Exsolution textures
Replacement textures
Open Fill Textures
Weathering

Question 20

may result from direct crystallization, fractionation, crystal settling, filter pressing, and other magmatic ore forming processes

Answer 20

Magmatic Ore Textures

Question 21

ores in which samples have rather homogeneous character and feature, and usually made up of one or few minerals

Answer 21

Massive Texture

Question 22

texture in which dissemination of minerals accumulate through the sample

Answer 22

Disseminated Texture

Question 23

ore in which ore minerals or disseminations of ore minerals accumulate as bands of mm to cm in thickness

Answer 23

Bands or Laminated Texture

Question 24

ore in which minerals are formed at the surface and have the kidney-like shape

Answer 24

Nodular Texture

Question 25

Under Nodular texture

mm size

Answer 25

Oolitic texture

Question 26

Under Nodular texture

cm size

Answer 26

Pisolitic texture

Question 27

simultaneous capillary solution and deposition by which a new mineral of partly or wholly differing chemical composition may grow in the body of an old mineral

Answer 27

Replacement/Metasomatism

Question 28

Rules for Replacement

Answer 28

1. Sulfides/Arsenides/Tellurides/Sulfosalts can replace any rock, gangue or ore minerals
2. Oxides replace all rock and gangue but are rarely replaced by gangue
3. Gangue minerals replace rock and other gangue but do not commonly replace sulfides/arsenides/tellurides/sulfosalts
4. Oxides rarely replace sulfides/arsenides/tellurides/sulfosalts

Question 29

a mineral or mineral aggregate retaining the outward form proper to a pre-existing mineral or mineral aggregate which it has replaced

Answer 29

pseudomorphs

Question 30

widening of a fracture filling to an irregular mass where a fracture crosses a chemically reactive mineral grain or rock

Answer 30

Replacement textures

Question 31

leading edge of front of replacement which has not completed

Answer 31

Vermicular Intergrowths

Question 32

varying diffusion rates of ions at the replacement front

Answer 32

Cusp and Caries texture