A cavity or vesicle formed by the presence of trapped gas, in igneous rock, that is filled with such secondary minerals as calcite, quartz, chalcedony, or zeolites
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Tag: <span>A</span>
Two or more metals together in a compound
Containing amygdules. See Amygdule
A mineral group including actinolite, anthophyllite, arfvedsonite, cummingtonite, hornblende, richterite, glaucophane, grunerite, anthophyllite, riebeckite, tremolite, and others
The gradual and systematic reduction of a balance in an account over an assigned period
Rocks or minerals lacking crystal structure or form
A variety of translucent to transparent purple to grey coloured quartz common as a semiprecious gemstone. The color results from with ferric iron substitution for silicon
The surrounding or encompassing and current state of an area
Metal cast in a shape suitable for refining by electrolytic process
Annual financial statements issued by a corporation to its shareholders pertaining to the activity of the company for that year