방연석(갈레나) Galena

원산지 : Reynolds County, Missouri, U.S.A.

크기(Dims) : 8.6 x 6.9 x 4.1 cm

방연석(THE MINERAL GALENA)

광물명: 방연석(Galena)

화학식(Chemistry): PbS PbS, Lead Sulfide

분류(Class): 황화광물(Sulfides) ,그룹(Group): 방연광(Galena)

사용처(Uses): 납과 은의 주요원광(Major ore of lead and silver)

화학적물리적특징(PHYSICAL CHARACTERISTICS)

- 색상은 납이나은회색이지만 때때로 푸른색을 보이기도 한다

- 광택은 금속이 풍화된 모양의 광택이 있다

- 투명도 : 투명 또는 불투명한 결정

- 결정구조는 등축결정

- 굴절률 연마편자료: 등방성

- 결정모양 : 큐브와 팔면체 두 조합을 포함하는 모양을 가지고 있으며, 스피넬과 같은 평평결정도 가능하다. 또한 입상의 형태도 있다.

- 벽개 : 하나의 완전한 벽개(단구벽개) 쪼개짐은 네방향으로 큐브모양이다. 정벽 결정형(6면체 결정)： 쪼개지기 쉬운 괴상

- 모스경도는(Hardness) 2.5+

- 비중은(Specific Gravity is approximately) 7.5+ 일반 금속광물보다 무겁다

- 조흔색은 회색이다.

- 관련광물은 방해석, 돌로마이트,섬아연석,황철석,그리고 황화광물이다.

- 기타특징은 다른광물에 절단면이나 표면이 밝은 광택면을 가진다

- 유명산지 : 텍사스, 오클라호마, 미조리등의 미국과 독일, 페루, 멕시코, 잠비아, 영국

This hand specimen consists of a single large Galena crystal that is in reasonably good condition. It shows definite abrasions on a few edges and corners and appears to be cleaved on two faces- however, though these cleaved faces have a brighter metallic luster than the intact ones, the luster is partly dulled, making me believe that the breakage occurred prior to mining. The undamaged faces and edges show good cubic crystal form, with well-defined edges and clean faces that show heavy patterning. The crystal has the classic dark gray color and high density of its species and is accompanied by only a small amount of the original brown shale host rock.

THE MINERAL GALENA

·    Chemistry: PbS, Lead Sulfide

·    Class: Sulfides

·    Group: Galena

·    Uses: Major ore of lead and silver

Galena is a common and popular mineral for rock hounds. Its characteristic cubes, distinctive cleavage and high density make it easy to identify and a favorite in high school geology labs. The structure of Galena is identical to that of halite, NaCl. The two minerals have the same crystal shapes, symmetry and cleavage. Some Galena may contain up to 1% silver in place of lead. The large volume of Galena that is processed for lead produces enough Silver as a by product to make Galena the leading ore of Silver.

To quote Allen N Wollscheidt,

"Galena, back 75 years ago, was the stuff -- the crystal -- of crystal radio sets. Surely you have heard of these -- possibly your grand or greatgrandparents built radio receivers out of round Quaker Oats boxes, a few feet of copper wire, a pair of headphones and a little "cats-whisker-with crystal" gadget from the hardware store. Some worked so well, they could be heard across the room.

Galena is a natural semiconductor and so the forerunner, the enabler, of all the electronic gadgets we have today, from telephones to TVs to GPS navigating systems as well as all sorts of medical equipment -- in short, modern life as we know it.”

PHYSICAL CHARACTERISTICS:

·    Color is lead to silver gray sometimes with a bluish tint.

·    Luster is metallic to dull in weathered faces.

·    Transparency crystals are opaque.

·    Crystal System is isometric; 4/m bar 3 2/m

·    Crystal Habits include the cube, octahedron and combinations of the two. Spinel twinning is possible forming flattened crystals. Also massive and granular.

·    Cleavage is perfect in four direction forming cubes.

·    Fracture is uneven and rarely seen because of the perfect cleavage.

·    Hardness is 2.5+

·    Specific Gravity is approximately 7.5+ (heavy even for metallic minerals)

·    Streak is lead gray

·    Associated Minerals are calcite, dolomite, sphalerite, pyrite and other sulfide minerals, also lead oxidation minerals such as cerussite and anglesite.

·    Other Characteristics: brighter metallic luster on cleavage surfaces than on crystal faces.

·    Notable Occurances include Texas-Oklahoma-Missouri area, USA; Germany, Peru, Mexico, Zambia, and England.