The Streak of Minerals

Streak plates alongside pyrite (left) together with rhodochrosite (right)
The streak (also called “powder color”) of a mineral is the color of the pulverization produced when it is dragged across an unweathered surface. This trail’s color by together with large is much to a greater extent than consistent than that of its rear mineral together with thence is an of import mineral identification tool. If no streak appears, together with then the mineral’s streak is said to hold upward white or colorless. Streak is particularly of import for identifying opaque together with colored materials together with is less useful for silicate minerals, virtually whereof convey a white streak together with are likewise difficult to easily powder.

The apparent color of a mineral tin greatly vary because of draw impurities or a disturbed macroscopic crystal structure. Small amounts of an impurity that strongly absorbs a item wavelength tin radically modify the wavelengths of low-cal that the specimen reflects, thereby changing the apparent color. Dragging the specimen to create a streak breaks into randomly oriented microscopic crystals, reducing the pocket-size impurities’ effect.

The surface whereover the mineral is dragged is called a “streak plate” together with by together with large is made from unglazed porcelain tile. The unglazed underside of a porcelain bowl or vase or the dorsum of a glazed tile also works. Sometimes a streak is to a greater extent than easily or accurately described yesteryear comparison it alongside the “streak” made yesteryear or so other streak plate.