|
| Formula | CaSiO3 |
| | Optic class & sign | Biaxial negative |
| | Optical orientation | b ≈ Y, moderate to high angles between a and Z, c and X |
| | Optical plane | (010) approx. |
| | Relief | Moderate positive |
| | Refractive indices | nx = 1.615 -1.646
|
|
ny = 1.627 -1.659
|
|
nz = 1.629 -1.662
|
|
| n increases with Fe and Mn |
| | Birefringence (max.) | 0.013 - 0.017 |
| | | Δn increases with Fe |
| | Optic Angle
| 2Vx
= 35 - 63° |
| | 2Vz
|
| | Sign of elongation | Length-slow, l (+) and length-fast l (-) as crystals are elongate in b ≈ Y. |
| | Interference figure | Broad isogyres with lower first-order isochromes; optic-axis or acute bisectrix figures can be obtained from elongate sections showing zero to low Δn |
| | Colour / pleochroism | Colourless |
| | Zoning | |
|
|
| Form | Habit | Columnar, bladed, fibrous; elongate ∥ b |
| | | Surface | Commonly subhedral to euhedral |
| | Cleavage | {100} perfect, {001} and {102} good |
| | Twinning | Simple and multiple twins on {100} |
| | Extinction | Nearly straight, within 5°, to b-parallel {001} and {100} cleavage traces |
|
|
| Reaction textures | |
| | Alteration / decomposition | Pectolite, calcite, apophyllite |
|
|
| Occurence | Ign | |
| | | Met | Siliceous marble, calcsilicate rocks; skarn. Reaction zones between calcite marble and quartz-bearing rocks |
| | | Sed | |
| | | Hyd | |
| | | Other | |
|
|
| Distinctive properties | Low Δn, moderate n, paragenesis |
| | Additional comments | Rare structural modifications: parawollastonite and pseudowollastonite |
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