Jasper Jasper Jasper, an aggregate of microgranular quartz and/or chalcedony and other mineral phases, is an opaque, impure variety of silica, usually red, yellow, brown or green in color; and rarely blue. The common red color is due to iron(III) inclusions. The mineral aggregate breaks with a smooth surface and is used for ornamentation or as a gemstone. It can be highly polished and is used for items such as vases, seals, and snuff boxes. The specific gravity of jasper is typically 2.5 to 2.9. A green variety with red spots, known as heliotrope (bloodstone), is one of the traditional birthstones
Heliotrope (instrument) Heliotrope (instrument) The heliotrope is an instrument that uses a mirror to reflect sunlight over great distances to mark the positions of participants in a land survey. The heliotrope was invented in 1821 by the German mathematician Carl Friedrich Gauss. The word "heliotrope" is taken from the Greek: "helios" (), meaning "sun", and "tropos" (), meaning "turn". It is a fitting name for an instrument which can be used to "turn" incoming sunlight (via reflection). Heliotropes were used in surveys from Gauss's survey in Germany in 1821 through the late 1980s, when GPS measurements replaced the use of the heliotrope