So-called "Bosa" Quartz (Brittle Quartz) of the Gold-bearing Quartz Veins of the Konomai Mine in Hokkaido

Study on Quartz Aggregate 1

Abstract

Sometimes saccharoidal or lamellar quartz is contained in gold-bearing quartz veins. Such brittle quartz-aggregates from Konomai Mine are called “bosa” quartz.
“Bosa” quartz is easily broken and is barren. Its silica content is very high (about 98 percent). It is one of the bands of vein structure, and is classed into angular, lamellar, saccharoidal, and platy“bosa” quartz.
“Bosa” quartz does not exhibit an intergrowth with calcite. Adjoining quartz, kaolin and marcasite are recognized. If the calcite of quartz-calcite aggregates is dissolved, porous quartz aggregates……“bosa” quartz……will be formed. The ratio of the volume of quartz to calcite and the shape of the calcite strongly affect the type of “bosa” quartz.
The dissolution may be caused by a primary acidic condition and it may occur in the original quartz-calcite aggregates. Therefore, most of the “bosa” quartz is not formed in the crushed or oxydized zone of veins.