Rock (geology)

In geology, rock or stone is a naturally occurring solid aggregate of one or more minerals or mineraloids. For example, the common rock granite is a combination of the quartz, feldspar and biotite minerals. The Earth's outer solid layer, the lithosphere, is made of rock.

Rocks have been used by mankind throughout history. From the Stone Age, rocks have been used for tools. The minerals and metals found in rocks have been essential to human civilization.

Three major groups of rocks are defined: igneous, sedimentary, and metamorphic. The scientific study of rocks is called petrology, which is an essential component of geology.

Classification

At a granular level, rocks are composed of grains of minerals, which, in turn, are homogeneous solids formed from a chemical compound that is arranged in an orderly manner. The aggregate minerals forming the rock are held together by chemical bonds. The types and abundance of minerals in a rock are determined by the manner in which the rock was formed. Many rocks contain silica (SiO₂); a compound of silicon and oxygen that forms 74.3% of the Earth's crust. This material forms crystals with other compounds in the rock. The proportion of silica in rocks and minerals is a major factor in determining their name and properties.

Animal Crossing

Animal Crossing (どうぶつの森, Dōbutsu no Mori, lit. "Animal Forest"), is a community simulation video game series developed and published by Nintendo, in which the human player lives in a village inhabited by anthropomorphic animals, carrying out various activities including fishing, bug catching, etc. The series is notable for its open-ended gameplay and extensive use of the game systems' internal clock and calendar to simulate real passage of time. Four Animal Crossing games have been released worldwide, one each for the GameCube, Nintendo DS, Wii, and the Nintendo 3DS. The series has been both critically and commercially successful and has sold 23.711 million units worldwide. Two new games, titled Animal Crossing: Happy Home Designer and Animal Crossing: Amiibo Festival, have been released for Nintendo 3DS and Wii U respectively; both are spin-offs of the series and they were released in 2015.

Gameplay

In all of the Animal Crossing games, the player assumes the role of a human character, who moves into a rural village populated with anthropomorphic animals and lives there indefinitely. Gameplay is open-ended: players have no defined objectives, but are instead encouraged to spend their time in the village performing any number of activities, which include collecting items, planting plants or other items, and socializing with the village's residents. All Animal Crossing games are played in real time, utilizing the system's internal clock and calendar. Thus, passage of time in the game world reflects that in reality, as well as the current season and time of day. Some in-game events, such as holidays or the growth of a tree, occur at certain times or require some duration of time to have passed.