Glossary of Rock and Mineral Terms - K

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

 

K. or Kt.

Abbreviation of karat.

karat

Unit of measurement describing the content of gold in an ornament. The karat unit measures the percentage of gold in metallic objects made of gold (mainly jewelry). Since pure gold bends too easily, it is mixed with tougher metals when made into ornaments to form a tougher, although impurer, gold. The karat measurement determines the percentage of gold on a 1 to 24 scale, with 24 karats being pure gold. That means that 14 karat gold is only 14/24 (or 58.33%) gold. Gold with a high karat measurement is undesirable for jewelry because it is soft and bendable, and gold with a low karat measurement is undesirable because of its low gold content [hence lesser value]. The term karat can be confused with the term carat, which is the weight measurement for gemstones. The abbreviation of karat is k. or kt.

karst

A topography characterized by caves, sinkholes, disappearing streams, and underground drainage. Karst forms when groundwater dissolves pockets of limestone, dolomite, or gypsum in bedrock.

kerogen

A solid, waxy, organic substance that forms when pressure and heat from the Earth act on the remains of plants and animals. Kerogen converts to various liquid and gaseous hydrocarbons at a depth of 7 or more kilometers and a temperature between 50º and 100ºC.