What does the word matrix mean?

Usage examples for matrix

  1. They are, however, at present almost destitute of tools for moving the soil, and of washing implements for separating the gold from the earthy matrix, and have therefore to pick it out with their knives, or to use their fingers for that purpose; a circumstance which in some measure accounts for the small products of gold up to the present time, the export being only about 300 ounces since the 6th of last October. – Handbook to the new Gold-fields by R. M. Ballantyne
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