1 Dehydration. 2  Not staying hydrated with enough water during the day may be one of the big causes of leg cramps at night. 3  This is most likely due to fluid imbalances of electrolytes (mainly sodium, potassium, calcium, and magnesium).4  Overuse of the muscles, perhaps from exercising, gardening or other physical activities. Dehydration. 2  Not staying hydrated with enough water during the day may be one of the big causes of leg cramps at night. 3  This is most likely due to fluid imbalances of electrolytes (mainly sodium, potassium, calcium, and magnesium).
Lustre (mineralogy) Lustre or luster is the way light interacts with the surface of a crystal, rock, or mineral. The word traces its origins back to the latin lux, meaning light, and generally implies radiance, gloss, or brilliance. A range of terms are used to describe lustre, such as earthy, metallic, greasy, and silky. Similarly, the term vitreous (derived from the Latin for glass, vitrum) refers to a glassy lustre. A list of these terms is given below. Lustre varies over a wide continuum, and so there are no rigid boundaries between the different types of lustre.
2) STREAK. This is the colour of the line drawn when a mineral is rubbed across a piece of unglazed tile. Often the line is the same or similar colour of the specimen.This test is useful because in a few cases, similar looking minerals have different streaks - so this test is a definitive identifier. Luster is what the surface looks like when the light reflects off of the mineral. Some words to describe luster are: 1  DULL / EARTHY - very dull, mainly minerals that are porous eg kaolinite, orthoclase.  WAXY - like the surface of a candle, like wax paper eg opal, chalcedony.