What causes some minerals to have high or low relief?

What causes some minerals to have high or low relief?

Mineral relief is related to the refractive index of the mineral. If a mineral has a refractive index that is much higher or lower than the surrounding materials, it will stand out relative to the surrounding material and will have thick or distinct .

What is a relief geology?

‘Relief’ is the term used for the differences in height from place to place on the land’s surface and it is greatly affected by the underlying geology. Relief relies on the hardness, permeability and structure of a rock. High Force waterfall, Teesdale, County Durham.

What is a negative relief?

If a mineral has a lower refractive index than its surroundings, it is said to have negative relief, and if the mineral’s refractive index is higher that the enclosing medium, the mineral has positive relief.

What is positive relief?

a relatively elevated irregularity on the earth’s surface, lying above the average hypsometric level of the adjacent land area, such as a mountain range or upland, or above the average bathymetric level of the adjacent ocean floor.

Does quartz have high relief?

Most of this view shows quartz. It is characterized by low relief (PP), undulatory extinction (XP) and low order interference colors (XP). The brownish, high-relief grains (PP) are rutile. Rutile has very high birefringence but the color of the grain is so strong that its interference colors don’t show (XP).

What is the relief of quartz?

Quartz has low relief and is colourles and therefore undistinctive in PPL. In XPL it shows 1st order greys, up to 1st order yellow.

What is relief in geography definition?

Relief is the variations in the elevation of the ground surface, also features of height above a plain or reference datum. On a relief map, relief is depicted by hachures or shading, or, more accurately, by contours or by spot elevations or both.

What is low relief landscape?

Equilibrium low-relief surfaces are typically found at low elevations, graded to sea level. However, there are many examples of high-elevation, low-relief surfaces, often referred to as relict landscapes1,2, or as elevated peneplains3.

What is a high relief mineral?

Relief refers to the way a mineral appears to “stand out” when viewed in PP light. Sometimes we refer to a mineral as having high relief or low relief. Minerals with high relief have sharp grain boundaries, show fractures and cleavages well, and sometimes appear to stick out above other minerals in the thin section.

What is a relief feature in geography?

In geography, the sense of relief implies the highest and lowest elevation points in a particular region. Mountains & ridges and valleys are elevated points of elevation and are examples of low lying areas.

What is low relief in geology?

“Relief” is essentially the opposite of “flatness”. Relief is typically defined as the difference in height between the high point and the low point on a landscape, in feet or in meters. It could also be defined more qualitatively: like “low relief plains” or “high relief rolling hills”.

Does plagioclase have high relief?

High -ve relief, colour and isotropy distinctive. plagioclase crystals. Colourless and nearly isotropic distinctive.