螺状硫银矿

{{infobox mineral
| name = 螺状硫银矿
| category = 硫化物矿物
| boxwidth =
| boxbgcolor =
| image = Acanthite - Imiter mine, Jbel Saghro, Tinghir, Drâa-Tafilalet, Morocco.jpg
| imagesize = 280px
| alt =
| caption = 来自摩洛哥山脉Imiter矿的结晶螺状硫银矿（4.0 × 2.5 × 1.5 cm）
| formula = Ag2S
|IMAsymbol=Aca
| molweight =
| strunz = 2.BA.30a
| dana =
| system = 单斜
| class = 棱柱形 (2/m)
（H-M记号相同）
| symmetry = P21/n
| unit cell = a = 4.229 Å, b = 6.931 Å
c = 7.862 Å; β = 99.61°; Z = 4
| color = 铁黑色
| colour =
| habit = 初生晶体稀有，棱柱状到长棱柱状，沿[001]伸长，可能呈管状；大量的。通常在立方高温相之后变质（“辉银矿”），具有原始立方或八面体晶形
| twinning = {101}接触
| cleavage = 模糊
| fracture = 参差状
| tenacity = 脆
| mohs = 2.0 - 2.5
| luster = 金属光泽
| streak = 黑色
| diaphaneity = 不透明
| gravity = 7.20 - 7.22
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螺状硫银矿（）是硫化银的一种形式，化学式为Ag2S。它以单斜晶系结晶，在以下是稳定的硫化银形式。辉银矿是高于该温度的稳定形式。当辉银矿冷却到该温度以下时，它的立方形态会变形为单斜晶系的螺状硫银矿。低于173°C时直接形成螺状硫银矿。螺状硫银矿是正常气温下唯一稳定的形式。

产生
螺状硫银矿是中低温热液脉和表生富集带中常见的银矿物。它与自然银、浓红银矿、淡红银矿、硫锑铜银矿、脆银矿、辉硒银矿、方铅矿、黄铜矿、闪锌矿、方解石和石英一起出现。

圖集
File:Acanthite - Chispas Mine, Arizpe, Sonora, Mexico.jpg|螺状硫银矿 - 产地：墨西哥索诺拉州Chispas矿。比例尺为一英寸，格线為1 cm。
File:Acanthite-180757.jpg|来自墨西哥瓜纳华托州Rayas矿的经典螺状硫银矿标本。尺寸：2.4 x 1.1 x 1.1 cm。

参考资料