35億年

化學組成, 鍵及結構：(礦物)

3.5 billion years

Chemical composition, bonding and structure: (Mineral)

高等級意味著變質作用發生在高壓和320攝氏度或更高的溫度。礦物預變質作用中存在的任何水體隨著溫度的升高而經常喪失，從而形成一般難以溶解於水中的硬質變質岩。區域意味著變質條件發生在大的地理區域，並且包括差異（或剪切）應力，這有助於形成稱為葉理的分層結構。片麻岩顯示出一種獨特的葉理，稱為片麻狀帶，這是比大多數變質岩顯示的更厚的葉面帶。這是幫助區分片麻岩與其他葉狀岩石的特徵之一。礦物學上，片麻岩往往包括石英，長石，雲母，綠泥石和其他粘土礦物。有些還含有嵌在岩石基質中的較大晶體，最常見的是石榴石，黃玉和綠柱石礦物。

原生物：(化石)

High grade means that the metamorphism occurs at high pressures and at temperatures at or above 320 degrees Celsius. Any water that is present in the minerals pre-metamorphism is frequently lost as the temperature increases, resulting in hard metamorphic rocks that are generally resistant to dissolution in water. Regional means that the metamorphic conditions occur over large geographic areas and include differential (or shearing) stresses, which help to form the layered structure known as foliation. Gneiss rocks exhibit a unique form of foliation known as gneissic banding, which are thicker bands of foliation than most metamorphic rocks display. It is one of the features that helps differentiate gneiss from other foliated rocks. Mineralogically, gneiss tends to include quartz, feldspar, mica, chlorite, and other clay minerals. Some also contain larger crystals imbedded in the rock matrix, most frequently garnet, topaz, and beryl minerals.

Living Specimens: (Fossil)

但大多數標本都有長石和石英顆粒的帶狀結構。 這些樂隊通常是淺色的，並與深色的礦物帶有交替，帶有片狀或細長的習慣。 黑色礦物有時表現出由變質壓力決定的取向。

一些片麻岩標本含有變質環境特徵的獨特礦物。 這些礦物可能包括黑雲母，堇青石，矽線石，藍晶石，十字石，紅柱石和石榴石。

The dark minerals sometimes exhibit an orientation determined by the pressures of metamorphism.

Some specimens of gneiss contain distinctive minerals characteristic of the metamorphic environment. These minerals might include biotite, cordierite, sillimanite, kyanite, staurolite, andalusite, and garnet.

美觀堅固 明顯的線條美 是良好的建築材料

Beautiful and solid

The obvious line beauty is a great building material

片麻岩分佈很廣，在區域變質岩地區經常出現，在中溫和高溫情況下都可以形成

Gneisses are widely distributed and often occur in regional metamorphic rock areas and can be formed in both moderate and high temperatures.