carbonate -dolomite group

Question 1

dolomite-ankerite formula

Answer 1

Ca(Mg,Mn,Fe)(CO3)2

Question 2

dolomite-ankerite crystal form

Answer 2

dolomite
- usually rhombohedra with curved faces
if strongly curved “saddle shaped” crystals
- other forms are rare
- coarse cleavable masses to fine compact

ankerite
- rarely in well formed crystals, but if yes, same with dolomite

Question 3

dolomite-ankerite cleavage

Answer 3

rhombohedral perfect

Question 4

dolomite-ankerite hardness

Answer 4

3.5 to 4

Question 5

dolomite-ankerite specific gravity

Answer 5

• dolomite: 2.85
• ankerite: 3.1

Question 6

dolomite-ankerite color

Answer 6

dolomite: colorless, white, gray, green, light pink, flesh
ankerite: vitreous, transparent to translucent, yellowish white, yellowish brown (bc of iron oxidation)

Question 7

dolomite-ankerite occurrence

Answer 7

dolomite: dolomite/dolostone, dolomitic marble, hydrothermal vein mineral, esp in lead/zinc veins in limestone, associated with calcite, siderite, barite, fluoride

ankerite: common carbonate in precambrian iron formations associated with chert, hematites and magnetite

Question 8

dolomite-ankerite remarks

Answer 8

• color difference between dolomite and ankerite
• effervesce and soluble with hot HCl and powdered with cold HCl
• crystal variety: curved faces and pink
• massive vs limestone: less reactive to HCl

Question 9

malachite formula

Answer 9

Cu2CO3(OH)2

Question 10

malachite crystal form

Answer 10

• slender monoclinic prismatic crystals, seldom distinct
• pseudomorphous after azurite
• stalactitic or botryoidal with radiating fibers
  -granular or earthy

Question 11

malachite hardness

Answer 11

3.5 to 4

Question 12

malachite specific gravity

Answer 12

3.9 to 4.03

Question 13

malachite color

Answer 13

• adamantine to vitreous. translucent
• silky for fibrous
• dull for earthy
• bright green with pale green streak

Question 14

malachite occurrence

Answer 14

supergene copper mineral in oxidized portions of copper veins associated with azurite, cuprite, iron oxides and native copper

Question 15

malachite remarks

Answer 15

• effervesce in cold HCl
• green and botryoidal

Question 16

azurite chemical formula

Answer 16

Cu3(CO3)2(OH)2

Question 17

azurite crystal form

Answer 17

• monoclinic, complex and malformed
• radiating spherical groups

Question 18

azurite cleavage

Answer 18

prismatic perfect, pinacoidal fair

Question 19

azurite hardness

Answer 19

3.5 to 4

Question 20

azurite specific gravity

Answer 20

3.77

Question 21

azurite color

Answer 21

vitreous transparent to translucent. intense azure blue

Question 22

azurite occurrence

Answer 22

less common than malachite but same origin and associations

Question 23

azurite remarks

Answer 23

• in association with malachite, azure blue color, hardness and effervescence with cold HCl