carbonate - aragonite group

Question 1

aragonite crystal form

Answer 1

• orthorhombic
  3 common habits
• acicular pyramidal, radiating group of minerals
• tabular, prominent vertical pinacoids and prisms
• cyclic hexagonal like twins with basal plane, striated in 3 directions
  -reniform, stalactitic and columnar

Question 2

aragonite cleavage

Answer 2

prismatic poor, pinacoidal distinct

Question 3

aragonite hardness

Answer 3

3.5 to 4

Question 4

aragonite specific gravity

Answer 4

2.95

Question 5

aragonite color

Answer 5

vitreous translucent transparent. colorless white pale yellpw

Question 6

aragonite occurrence

Answer 6

• less common than calcite
• associated with gypsum
• hot springs deposits
  -amygdaloidal cavities in basalt
  -fibrous crusts of serpentines
  -blueschist facies (low temp high p)
  -pearly layers on shells and pearls themselves

Question 7

aragonite remarks

Answer 7

• effervesce in cold HCl
• no distinctive flame discoloration

Question 8

aragonite formula

Answer 8

CaCO3

Question 9

witherite formula

Answer 9

BaCO3

Question 10

witherite crystal formula

Answer 10

• orthorhombic, twins on the 110
• pseudohexagonal, dipyramids by intergrowth of 3 minerals
• deeply horizontally striated
• botryoidal, columnar granular

Question 11

witherite cleavage

Answer 11

prismatic poor, pinacoidal distinct

Question 12

witherite hardness

Answer 12

3.5

Question 13

witherite specific gravity

Answer 13

4.3

Question 14

witherite color

Answer 14

vitreous translucent to transparent colorless white gray

Question 15

witherite occurrence

Answer 15

hydrothermal veins associated with galena

Question 16

witherite remarks

Answer 16

• soluble in cold HCl
• yellowish-green flame test

Question 17

strontianite formula

Answer 17

SrCO3

Question 18

strontianite crystal form

Answer 18

• orthorhombic radiating acicular crystals
• twinned on the 110, pseudohexagonal
• columnar, granular, fibrous

Question 19

strontianite cleavage

Answer 19

prismatic good

Question 20

strontianite hardness

Answer 20

3.5 to 4

Question 21

strontianite specific gravity

Answer 21

3.7

Question 22

strontianite color

Answer 22

vitreous translucent to transparent. white yellow gray green

Question 23

strontianite occurrence

Answer 23

• low temp hydrothermal veins associated with barite, celestite and calcite
• sulfide veins
• rare in igneous rocks

Question 24

strontianite remarks. how to distinguish from celestite

Answer 24

• effervesce in cold HCl
• red flame test
• poorer cleavage and effervescence

Question 25

cerussite formula

Answer 25

PbCO3

Question 26

cerussite crystal form

Answer 26

• orthorhombic, more varied
• tabular on 010
• reticulated crossing @ 60 degrees
• pseudohexagonal twins with reentrant angles in vertical zone
• granular, compact, fibrous, earthy

Question 27

cerussite cleavage

Answer 27

3 to 3.5

Question 28

cerussite specific gravity

Answer 28

6.65

Question 29

cerussite color

Answer 29

adamantine transparent to subtranslucent. colorless white gray

Question 30

cerussite occurrence

Answer 30

• supergene lead ore associated with primary minerals like galena and sphalerite

Question 31

cerussite remarks

Answer 31

high specific gravity and adamantine luster