较软的天然石材有哪些？它们可以在哪里使用？景观石

为什么有些 天然宝石 considered to be soft when they all appear to be hard? The answer lies within ‘relative’ hardness. Mohs scale of hardness was invented in 1812 and compares the relative hardness of ten minerals. Diamond is the hardest and rates a 10, while granite is the toughest natural stone at 6. Limestone comes in at 3 as does its metamorphic counterpart, marble. Softer stone is easier to dress or carve but does not wear or weather quite as well as harder stone. Here we discuss some of the more popular soft stones along with suitable applications.

不规则的石头

沉积岩

石灰岩、砂岩和页岩是最常见的沉积岩类型。它们是由数百万年来巨大的压力作用于沉降到海底的沉积物而形成的。

石板

The layers in slate are described as being “foliated” and they are easily split apart to create whatever thickness is required. UK slate is considered to be hard and was traditionally used as roofing, while soft slate is found in China, Spain, Italy and the USA. With a broad range of natural slate colours, a multiple array of designs can be achieved, from contemporary to classic, rustic to refined. Slate is often recommended for high traffic areas, thanks to its remarkably durable composition. It is also non-porous and does not easily react with acid liquids. It is fire proof, weather resistant and achieves good slip resistance dues to its riven finish.

石灰石

Limestone is a very common building material and is formed mainly from the mineral calcite, derived from the calcium in bones and seashells deposited over the millennia and forced together through pressure. While it also contains magnesium, it is harder and more weather resistant, and can also be polished. Portland stone from the eponymous island in Dorset is probably the single most famous type of limestone and was used to build many of London’s great buildings. It is used for external cladding as well as paving, fireplaces and other internal and external decorative features. Its soft colours are its trademark visual attributes.

砂岩

砂岩可能是 1800 年之前最常用的建筑石材，用于建造从桥梁到庄严的建筑等各种建筑。从其名称可以看出，它是在数千年的时间里，沙子、有机物、方解石和各种其他矿物质在巨大的压力下融合在一起而形成的。砂岩有粗糙或细腻的质地，传统上以哑光饰面供应。在英国，砂岩主要呈乳白色、红色或灰色，其颜色取决于其中所含的其他矿物质。二氧化硅使砂岩呈白色，而铁会使砂岩呈红褐色。其主要应用领域是墙壁和地板，或外部铺路。

大理石

大理石是石灰石的衍生物，经过数百万年的巨大热量和压力的变质而形成。虽然大理石与其他石头相比相对较软，但抛光效果非常好。传统上，大理石用于门，有助于打造高端饰面。