Malachite / Chrysocolla

Object/Artifact

-

Crater Rock Museum

Name/Title

Malachite / Chrysocolla

Entry/Object ID

1984.62.12

Description

Chemical Composition: Cu2(CO3)(OH)2 / CuSiO3 - Crystal System: Monoclinic System Description: Common Name: Malachite / Chrysocolla Chemistry: Cu2(CO3)(OH)2 / CuSiO3 - nH2 O Class: Carbonates / Silicates Location: Arizona Description: Smooth back with two polished sides. Blue-green, black and tans in an uneven mix. Physical Description: (Malachite) •Color is banded light and dark green or (if crystalline), just dark green. •Luster is dull in massive forms and silky as crystals. •Transparency is opaque in massive form and translucent in crystalline forms. •Crystal System is monoclinic; 2/m. •Crystal Habitsin its massive forms are botryoidal, stalactitic or globular. Crystals are acicular or fibrous and form in tufts and encrustations. Frequently found as pseudomorphs of azurite. •Cleavage is good in one direction but rarely seen. •Fracture is conchoidal to splintery. •Hardness is 3.5-4. •Specific Gravity is 3.9+ (slightly heavy). •Streak is green. •Other Characteristics: Weakly effervesces in acid. •Associated Minerals include limonite, chalcopyrite, bornite, native copper, calcite, cuprite, azurite, chrysocolla and many rare copper minerals such as kolwezite, shattuckite, antlerite, brochantite, graemite, aurichalcite, sphaerocobaltite, atacamite, chalcophyllite, conichalcite, rosasite, chalcosiderite, clinoclase, cornetite, duftite, libethenite, liroconite, mixite and mottramite among others. •Best Field Indicators are color banding, softness, associations and reaction to acid. Physical Description (Chrysocolla) •Color is a unique green-blue but can vary widely from more blue to more green, often in the same specimen. •Luster is earthy to dull or vitreous and waxy. •Transparency specimens are translucent to opaque. •Crystal System is probably monoclinic or orthorhombic. •Growth Habits include mostly massive forms that can be crusts, stalachtites and botryoidal. Also as inclusions in other minerals such as quartz. •Cleavage is absent. •Fracture is pronounced conchoidal. •Hardness is variable from 2 to 4. •Specific Gravity is approximately 2.0 - 2.3 (very light) •Streak is white to blue-green. •Associated Minerals are quartz, limonite, azurite, malachite, cuprite and other secondary copper minerals. •Other Characteristics: may have an opal like appearance. •Best Field Indicators are lack of crystals, color, fracture, low density and softness. Fracture: Conchoidal Hardness: 7 Quartz Luster: Silky Rock Type: Sedimentary Specific Gravity: 3.9+ Streak: Green Variety: May have opal-like appearence

Collection

Leland "Cap" Mentzer

Acquisition

Accession

1984.62

Source or Donor

Leland "Cap" Mentzer

Acquisition Method

Long-term Loan

Dimensions

Width

2-1/2 in

Depth

1-3/4 in

Length

4 in

Location

Location

Container

Left

Drawer

Top Shelf

Shelf

Center, Center

Wall

North

Room

Mentzer Hall

Building

Mentzer Hall: "Caps Collectables" North case#9

Category

Permanent

Moved By

Steve Miller

Date

March 23, 2011

Location

Shelf

Middle

Cabinet

Case# 9

Building

Mentzer Hall: "Caps Collectables"

Category

Permanent