又谓之寒水石，纹理通彻，人或磨刻为枕，以备暑月之用。入药烧过，或市人烧入
腻粉中以乱真，不可不察也。陶隐居言∶夏月能为冰者佳，如此则举世不能得，似乎失言。
二书纷辨不决，未悉厥理。详《本经》元无方解石之说，正缘《唐本》注石膏、方解
石大体相似。因此一说，后人遂惑。经曰∶生齐山山谷，及齐卢山、鲁蒙山。采无时，即知
他处者为非。今《图经》中又以汾州者编入，前后人都不详。经中所言细理白泽者良，故知
不如是，则非石膏也。下有理石条中经云∶如石膏顺理而细，又可明矣。今之所言，石膏、
方解石，二者何等有顺理细纹又白泽者。有是，则石膏也；无是，则非石膏也。仍须是经中
所
言州土者，方可入药，余皆偏见，可略不取。仲景白虎汤中，服之如神。新校正仲景《伤寒
论》后，言四月以后，天气热时，用白虎者是也。然四方气候不齐，又岁中气运不一，方所
既异，虽其说甚雅，当此之时，亦宜两审。若伤寒热病，或大汗后，脉洪大，口舌燥，头痛
，大渴不已；或着暑热，身痛倦怠，白虎汤服之无不效。
色轻紫，石上皲涩，可吸连针铁，俗谓之 铁石。养益肾气，补填精髓，肾虚耳聋目
昏皆用之。入药，须烧赤醋淬。其玄石，即磁石之黑色者也。多滑净。其治体大同小异，不
可分而为二也。磨针锋则能指南，然常偏东不全南也。其法取新纩中独缕，以半芥子许蜡，
缀于针腰，无风处垂之，则针常指南。以针横贯灯心，浮水上，亦指南，然常偏丙位。盖丙
为大火，庚辛金受其制，故如是，物理相感尔。
又被称为寒水石，纹理通透，有人将其磨刻成枕头，以备夏季使用。入药需经过煅烧，或者市面上有人将其烧制后混入轻粉中以假乱真，不可不仔细辨别。陶隐居说：夏天能结冰的才是上品，如果真是这样，那么天下人就都无法得到了，这似乎是不当的说法。
两本书争论不休，未能决断，不清楚其中的道理。详细考察《神农本草经》原本并没有关于方解石的记载，正是因为《唐本草》注释中说石膏和方解石大体相似。因此产生这一说法，后人于是感到困惑。经文说：生长在齐山山谷，以及齐卢山、鲁蒙山。采集没有固定时间，由此可知其他地方出产的不是正品。现在的《图经》中又将汾州出产的编入其中，前后的人都未详加考证。经文中说纹理细密、色泽白润的是佳品，所以知道如果不是这样，就不是石膏。在下文理石条目中经文说：像石膏那样顺着纹理且质地细腻，这一点也可以明白了。现在所说的石膏、方解石，二者有多少是具备顺理、细纹且白泽特征的？有这些特征，就是石膏；没有这些特征，就不是石膏。仍然必须是经文中所说的产地出产的，才可以入药，其余的都是偏见，可以不予采纳。张仲景的白虎汤中，服用它效果如神。新校正对张仲景《伤寒论》后的注释中提到，四月以后天气炎热时，使用的是白虎汤（指白虎汤证）。然而四方气候不同，每年运气也不一样，地域既然不同，虽然这种说法很雅致，但在此时，也应当双重审慎。如果是伤寒热病，或者大汗之后，脉象洪大，口舌干燥，头痛，极度口渴不止；或者是感受暑热，身体疼痛倦怠，服用白虎汤无不有效。
颜色呈浅紫色，石头表面皲裂粗糙，能够吸附针铁，俗称铁石。滋养肾气，填补精髓，肾虚导致的耳聋、目昏都使用它。入药必须烧红后用醋淬炼。其黑色的品种称为玄石，就是磁石中的黑色者。大多光滑洁净。它们的疗效大体相同小异，不能分为两类。磨尖针锋就能指南，然而常常偏东而不正南。其方法是取新丝绵中的单根丝缕，用半粒芥子大小的蜡，缀在针腰上，在无风处悬挂起来，则针常指南。将针横穿灯心草，浮在水面上，也能指南，然而常常偏向丙位。因为丙属大火，庚辛金受其制约，所以如此，这是物理相互感应的结果。
It is also known as *Hanshuishi* (Calcitum, 寒水石). Its texture is transparent and clear. Some people grind and carve it into pillows for use during the summer months. For medicinal use, it must be calcined. However, merchants sometimes calcine it and mix it with *Nifen* (Calomel, 腻粉) to pass it off as genuine; this requires careful examination. Tao Hongjing stated that the best quality is that which can form ice in summer. If this were true, no one in the world could obtain it, suggesting his statement was inaccurate.
The two texts debate without resolution, and the underlying principle remains unclear. A detailed examination of the *Shennong Bencao Jing* (Classic of Materia Medica) reveals no original mention of *Fangjieshi* (Gypsum Fibrosum var.). This confusion likely arose because the *Tang Bencao* (Tang Dynasty Pharmacopoeia) notes that *Shigao* (Gypsum Fibrosum) and *Fangjieshi* are largely similar. Consequently, later generations became confused. The classic states: "Grows in the valleys of Qi Mountain, as well as Qilushan and Lumen Mountain. Harvested at any time." From this, we know that those from other regions are not authentic. The current *Tujing* (Illustrated Records) includes specimens from Fenzhou, a point overlooked by previous scholars. The classic states that those with fine grain and bright white luster are superior. Thus, if they lack these characteristics, they are not *Shigao*. In the entry for *Lishi* (Magnesite), the classic mentions: "Similar to *Shigao*, following the grain and being fine," which clarifies this further. Among what is currently called *Shigao* and *Fangjieshi*, how many possess the qualities of following the grain, having fine texture, and exhibiting bright white luster? Those with these qualities are *Shigao*; those without are not. Furthermore, only those from the specific regions mentioned in the classic should be used medicinally. Others represent biased views and should be disregarded. In Zhang Zhongjing’s *Baihu Tang* (White Tiger Decoction), its efficacy is miraculous. The corrected annotations after Zhang Zhongjing’s *Shanghan Lun* (Treatise on Cold Damage Disorders) state that in late April, when the weather is hot, *Baihu Tang* is indicated. However, climates vary across regions, and annual qi movements differ. Given these geographical and temporal variations, although the theory is elegant, one must exercise double caution. For cold damage febrile diseases, or after profuse sweating, if the pulse is flooding (*Hong*), the mouth and tongue are dry, there is headache, and extreme thirst persists; or if suffering from summerheat, with body pain and fatigue, *Baihu Tang* is invariably effective.
Its color is light purple, the stone surface is cracked and rough, and it can attract needles and iron. It is commonly called *Tieshi* (Magnetite, 铁石). It nourishes kidney qi and replenishes essence and marrow. It is used for deafness and blurred vision caused by kidney deficiency. For medicinal use, it must be heated red-hot and quenched in vinegar. Its black variety is called *Xuanshi*, which is simply the black form of *Cishi* (Magnetitum, 磁石). It is mostly smooth and clean. Their therapeutic effects are largely identical with minor differences, and they should not be divided into two separate categories. When the tip of a needle is ground, it can point south, but it often points slightly east rather than due south. The method is to take a single thread from new cotton wool, attach it to the middle of the needle with a piece of wax the size of half a mustard seed, and hang it in a windless place; the needle will then consistently point south. Alternatively, threading the needle horizontally through a rush pith and floating it on water also makes it point south, though it often deviates toward the Bing position. This is because Bing belongs to Great Fire, and Geng/Xin Metal is controlled by it; thus, this phenomenon results from the mutual感应 (interaction/influence) of physical principles.