carbonate - aragonite group Flashcards
aragonite crystal form
- 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
aragonite cleavage
prismatic poor, pinacoidal distinct
aragonite hardness
3.5 to 4
aragonite specific gravity
2.95
aragonite color
vitreous translucent transparent. colorless white pale yellpw
aragonite occurrence
- 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
aragonite remarks
- effervesce in cold HCl
- no distinctive flame discoloration
aragonite formula
CaCO3
witherite formula
BaCO3
witherite crystal formula
- orthorhombic, twins on the 110
- pseudohexagonal, dipyramids by intergrowth of 3 minerals
- deeply horizontally striated
- botryoidal, columnar granular
witherite cleavage
prismatic poor, pinacoidal distinct
witherite hardness
3.5
witherite specific gravity
4.3
witherite color
vitreous translucent to transparent colorless white gray
witherite occurrence
hydrothermal veins associated with galena
witherite remarks
- soluble in cold HCl
- yellowish-green flame test
strontianite formula
SrCO3
strontianite crystal form
- orthorhombic radiating acicular crystals
- twinned on the 110, pseudohexagonal
- columnar, granular, fibrous
strontianite cleavage
prismatic good
strontianite hardness
3.5 to 4
strontianite specific gravity
3.7
strontianite color
vitreous translucent to transparent. white yellow gray green
strontianite occurrence
- low temp hydrothermal veins associated with barite, celestite and calcite
- sulfide veins
- rare in igneous rocks
strontianite remarks. how to distinguish from celestite
- effervesce in cold HCl
- red flame test
- poorer cleavage and effervescence
cerussite formula
PbCO3
cerussite crystal form
- orthorhombic, more varied
- tabular on 010
- reticulated crossing @ 60 degrees
- pseudohexagonal twins with reentrant angles in vertical zone
- granular, compact, fibrous, earthy
cerussite cleavage
3 to 3.5
cerussite specific gravity
6.65
cerussite color
adamantine transparent to subtranslucent. colorless white gray
cerussite occurrence
- supergene lead ore associated with primary minerals like galena and sphalerite
cerussite remarks
high specific gravity and adamantine luster
