Bilingual edition: English is preserved and Chinese follows each unit. Terminology uses the confirmed v20260916 glossary; automated semantic review remains traceable.
中英双语版：英文原文完整保留，中文紧随对应单元；术语采用 v20260916 确认表，自动语义审校结果可追溯。

Feldspar

长石

Plagioclase

Orthoclase
斜长石正长石

Feldspar is a name given to a class of aluminum-containing silicates which are sometimes called light silicates or "nonferromagnesian silicates" since they don't contain iron or magnesium. The feldspars include orthoclase (KAlSi3O8) and plagioclase ((Ca,Na)AlSi3O8). Note that the plagioclase differs from the orthoclase in terms of the additional metals, plagioclase having calcium or sodium and orthoclase having potassium. The feldspars have similar physical properties and typically have a luster ranging from glassy to pearly. They have two planes of cleavage meeting at or near 90° and are relatively hard, having Mohs hardness of about 6.

长石是一类含铝的硅酸盐的名称，有时也被称为轻质硅酸盐或'非铁镁质硅酸盐'，因为它们不含铁或镁。长石包括正长石（KAlSi₃O₈）和斜长石（(Ca,Na)AlSi₃O₈）。需要注意的是，斜长石与正长石的不同之处在于额外的金属元素，斜长石含有钙或钠，而正长石含有钾。长石具有相似的物理性质，通常具有从玻璃光泽到珍珠光泽的光泽。它们有两组解理面，交角约为90°，并且相对坚硬，莫氏硬度约为6。

Other members of the feldspar series are anorthite (CaAl2Si2O8) and albite (NaAlSi3O8). These are extreme members of the feldspar series.

feldspar系列的其他成员包括长石（CaAl₂Si₂O₈）和钠长石（NaAlSi₃O₈）。这些是feldspar系列的极端成员。

The feldspars are the most abundant minerals on the earth.

长石是地球上最丰富的矿物
Minerals
矿物
Selection of common minerals
常见矿物的选择
 Index

Lutgens & Tarbuck, Ch 2.
索引 Lutgens & Tarbuck，第2章。
 
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Plagioclase

斜长石

Plagioclase
斜长石

Plagioclase ((Ca,Na)AlSi3O8) is one of the forms of feldspar. It is an aluminum-containing silicate. This feldspar is distinguished from the orthoclase form by its content of calcium and sodium.

斜长石((Ca,Na)AlSi₃O₈)是长石的一种形式。它是一种含铝的硅酸盐。这种长石与正长石形式的区别在于其钙和钠的含量。

The feldspars are the most abundant minerals on the earth. In the Bowen reaction series, plagioclase can be seen to form throughout the process of magma crystallization in what is called the continuous reaction series. As the cooling continues, the calcium content of plagioclase diminshes while the sodium content increases.

长石是地球上最丰富的矿物。在博纳反应系列中，斜长石可以在岩浆结晶过程中形成，这一过程被称为连续反应系列。随着冷却的继续，斜长石中的钙含量减少，而钠含量增加。

The formation of plagioclase involves the substitution of an aluminum ion (Al3+) for a silicon ion (Si4+), while simultaneously substituting a calcium ion(Ca2+) for a sodium ion (Na1+) to preserve electrical neutrality.

形成斜长石涉及将一个铝离子（Al³⁺）替换为一个硅离子（Si⁴⁺），同时将一个钙离子（Ca²⁺）替换为一个钠离子（Na¹⁺），以保持电中性。

Plagioclase is usually white to light gray in color, although color is not a reliable mineral indicator. More definitive in distinguishing plagioclase from orthoclase is the presence of fine parallel lines called "striations" on plagioclase - these striations do not occur with orthoclase.

斜长石通常呈白色至浅灰色，尽管颜色并不是可靠的矿物鉴定指标。更可靠区分斜长石与正长石的是斜长石表面细平行条纹的特征——这些条纹正长石中并不出现。

Mindat: Plagioclase

Mindat: 斜长石


Minerals
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Orthoclase

斜长石

Orthoclase
斜长石

Orthoclase (KAlSi3O8) is one of the forms of feldspar. It is an aluminum-containing silicate. This feldspar is distinguished from the plagioclase form by its content of potassium .

正长石（KAlSi₃O₈）是长石的一种晶型。它是一种含铝的硅酸盐。这种长石与斜长石晶型的区别在于其钾的含量。

The feldspars are the most abundant minerals on the earth. Polycrystalline orthoclase is usually light cream to salmon pink in color, although color is not a reliable indicator of mineral type.

长石是地球上最丰富的矿物。多晶正长石通常呈浅奶油色到鲑鱼粉色，尽管颜色不是矿物类型的可靠指示器。

Orthoclase can form in single crystals like that shown at right, although the polycrystalline form above is the common occurrence. This crystal sample is about 5x3 cm and the gem is 61 carats. The sample is from Madagascar.

正交长石可以在像右边所示的单晶体中形成，尽管上面的多晶体形式是更常见的。这个晶体样本尺寸约为5x3厘米，宝石重61克拉。该样本来自马达加斯加。

The orthoclase sample at left is about 8x16 cm and is from Rhone Glacier, Aar Massif, Switzerland. It is of variety adularia. The sample at right is about 8x14 cm and is from St. Gotthare, Ticino, Switzerland. That sample is labeled as variety adularia with quartz and chlorite.

左图的正长石样品尺寸约为8x16厘米，采自瑞士阿尔卑斯山脉的罗纳冰川。该样品属于腺白长石品种。右图的样品尺寸约为8x14厘米，采自瑞士提契诺的圣戈塔雷。该样品被标注为腺白长石品种，伴有石英和云母。

The orthoclase sample above left is a single crystal about 4x4 cm from Binnatal, Valais, Switzerland. The sample above right is about 8x5 cm and is from Baveno, Italy. At left is a sample about 15x10 cm from Rhone Glacier, Aar Massif, Switzerland. It is identified as the variety adularia.

上图左侧的正长石样品是一个来自瑞士瓦莱州比纳塔尔的约4x4厘米的单晶体。上图右侧的样品约8x5厘米，来自意大利巴韦诺。左侧的样品约15x10厘米，来自瑞士阿尔卑斯山脉的罗纳冰川。该样品被鉴定为腺白长石品种。
These orthoclase gems are 249.5 and 126.4 carats and are from Madagascar.
这些正长石宝石重249.5和126.4克拉，来自马达加斯加。

This orthoclase sample is of variety adularia and is described as orthoclase with chlorite. It is about 20 cm wide and is from Grissons, Switzerland.

这种正长石样品属于腺岩变种，描述为正长石含云母。其宽度约为20厘米，产自瑞士格里森斯。

These gems are of the variety of orthoclase known as moonstone. From left above left are 119 carat and 45.5 carat gems from Sri Lanka. Next is a 4.8 carat gem from Burma. The next two gems are from Austria. The far right gem is 14.8 carats and is from Floiten Tal, Tirol, Austria. The carved gems below are 24.4 and 50.8 carats from Sri Lanka.

这些宝石属于正长石的一种，称为月光石。从左上到左依次是来自斯里兰卡的119卡特和45.5卡特的宝石。接下来是来自缅甸的4.8卡特的宝石。接下来的两颗宝石来自奥地利。最右边的宝石是14.8卡特，来自奥地利蒂罗尔的弗洛伊滕塔尔。下面雕刻的宝石来自斯里兰卡，分别为24.4卡特和50.8卡特。

Mindat: Orthoclase

Mindat: 正长石

Mindat: Moonstone

Mindat: 月光石
Minerals
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