| ペクトライト | |
|---|---|
 | |
| 一般 | |
| カテゴリ | イノケイ酸塩 鉱物 |
| 化学式 | NaCa 2 Si 3 O 8 (OH) |
| IMA記号 | Pct [1] |
| 結晶系 | 三斜晶系 |
| 結晶区分 | ピナコイド型（1） （HM記号と同じ） |
| 空間群 | P 1 |
| 単位胞 | a = 7.99Å、b = 7.03Å、 c = 7.03Å; α = 90.51°、 β = 95.21°、γ = 102.53°; Z = 2 |
| 識別 | |
| 色 | 無色、白っぽい、灰色がかった、黄色がかった |
| 晶癖 | 板状～針状、放射状の繊維状、球状、または柱状；塊状 |
| 双晶 | 双晶軸[010]、組成面[100]、共通 |
| 劈開 | {100}と{001}で完全 |
| 破壊 | 不均一 |
| 靭性 | 脆い；緻密な場合は強靭 |
| モース硬度 | 4.5～5 |
| 光沢 | 絹状、亜ガラス質 |
| 条線 | 白色 |
| 透明度 | 半透明～不透明 |
| 比重<extra_id_1> 2.84～2.90 | 光学特性 |
| 二軸性（+） | 屈折率 |
| n α = 1.594～1.610 n β = 1.603～1.614 n γ = 1.631～1.642 | 複屈折 |
| δ = 0.037 | 2V角 |
| 測定値：50°～63°、計算値：42°～60° | 分散 |
| r > v 弱い～非常に強い | 参考文献 |
| [2] [3] [4] | [2][3][4] |
Pectolite is a white to gray mineral, NaCa2Si3O8(OH), a sodium calcium hydroxide inosilicate. It crystallizes in the triclinic system typically occurring in radiated or fibrous crystalline masses. It has a Mohs hardness of 4.5 to 5 and a specific gravity of 2.7 to 2.9. A highly sought-after variety known as larimar, is a pale to sky blue. There is also a whitish form of the mineral from Alaska that is sometimes marketed as 'Alaska jade'.
Occurrence
It was first described in 1828 at Mount Baldo, Trento Province, Italy, and named from the Greek pektos – "compacted" and lithos – "stone".[3][4]
It occurs as a primary mineral in nepheline syenites, within hydrothermal cavities in basalts and diabase and in serpentinites in association with zeolites, datolite, prehnite, calcite and serpentine. It is found in a wide variety of worldwide locations.
See also
- Serandite – the manganese analogue
References
外部リンク
- 鉱物ギャラリー
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