• Chemistry: CaFe3OSi2O7(OH), Calcium Iron Silicate Hydroxide.
  • Class: Silicates
  • Subclass: Sorosilicates
  • Uses: mineral specimens
  • Specimens

Ilvaite is not a common mineral in rock shops. Its crystals are usually not all that attractive, but some specimens are real standouts with well-formed crystals with a shiny black color and an opaque submetallic luster. Its diamond-shaped crystals with wedge-like terminations can form very interesting specimens. Ilvaite is a member of the Sorosilicate subclass of the silicate minerals. Sorosilicates have an unusual basic unit of Si2O7. This group of atoms is composed of two silicate tetrahedrons that share one oxygen giving the group an hourglass shape. A fine specimen of ilvaite can be a valuable addition to anyones collection.


  • Color is normally black, but also brownish black to dark gray.
  • Luster is submetallic or resinous.
  • Transparency crystals are opaque.
  • Crystal System orthorhombic; 2/m 2/m 2/m
  • Crystal Habits include elongated crystals with an overall diamond-shaped cross-section and wedge-shaped terminations. Also as platy crystals and in massive, compact and columnar specimens.
  • Cleavage very poor, in one direction lengthwise.
  • Fracture is conchoidal.
  • Hardness is 5.5 - 6
  • Specific Gravity is 3.8 - 4.1
  • Streak is brownish black.
  • Associated Minerals are arsenopyrite, stilbite, hematite, magnetite and pyrite.
  • Other Characteristics: crystals are usually striated lengthwise.
  • Notable Occurances Rio Marina, Elba, Italy; Serifos, Greece; Idaho and Greenland.
  • Best Field Indicators crystal habit, color, hardness, cleavage and localities.
ILVAITE specimens:
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ILVAITE specimen ilv-1
$ 55.00
Dims: 1-1/8" x 3/4" x 5/8"
Wt: 15.3 g
Dalnegorsk, Siberia, Russia
Though the faces of this excellent little Ilvaite crystal are not the cleanest, it's not due to damage! Each of the 4 prism and 2 termination faces show heavy growth patterning as well as many minute crystals growing off their larger relative. The crystals are all black and opaque. The main crystal is double-terminated, with one of the terminations being damaged(it's where the crystal was attached to the host rock). This is rather uncommon, I believe, and certainly of exceptional quality.
no photo
ilv-1 ($ 55.00)
Dalnegorsk, Siberia, Russia
ILVAITE specimen ilv-2
$ 67.00
Dims: 0.8 x 0.8 x 0.6" (2.0 x 2.0 x 1.5 cm)
Wt: 19.0 g w/ specimen box
Dal'negorsk, Primorskiy Kray, Russia
This thumbnail specimen consists of 3 partly intergrown Ilvaite crystals. These crystals range in size from 0.4 x 0.2 x 0.2" (1.0 x 0.5 x 0.5 cm) to 0.9 x 0.7 x 0.6" (2.3 x 1.8 x 1.5 cm) and are in excellent condition, showing only one spot of damage where a small crystal broke off at its base. The mid-sized crystal is particularly interesting, as it grows off of the largest crystal at almost a right angle. All have excellent orthorhombic prismatic form, with edges and faces that appear to be somewhat disseminated, but are nontheless quite defined. Their color is black with subtle brown highlights, their luster is bright and almost adamantine, and they are opaque. There is no host rock present, and the specimen is hot-glued into a square plastic specimen box.
no photo
ilv-2 ($ 67.00)
Dal'negorsk, Primorskiy Kray, Russia
ILVAITE specimen ilv-3
$ 86.00
Dims:4.0x2.8x1.7" (10.1x7.1x4.3 cm)
Wt: 12.3oz. (350g)
Dal'Negorsk, Primorskiy Kray, Russia
This is a complex specimen. A thin layer of massive manganocalcite rest upon a matrix of long, fibrous hedenburgite crystals. Scattered over the manganocalcite are quartz, scalenohedral calcite, and ilvaite crystals. The largest ilvaite crystal measures 0.7" (1.8cm) in length. Finally, all of these minerals are covered with a layer of microcrystalline ilvaite. Some of the larger ilvaites are exposed so that the striated prism faces may be observed. There is only minor damage near the edges of this specimen.
no photo
ilv-3 ($ 86.00)
Dal'Negorsk, Primorskiy Kray, Russia
ILVAITE specimen ilv-4
$ 42.00
Dims:1.5x1.1x0.6" (3.8x2.8x1.5 cm)
Wt: 0.8oz. (22g)
Lvl 5, Los Remedios Mine, Taxco, Guerrero, Mexico
This specimen consists of a thick crust of ilvaite crystals with no matrix material. These crystals are black and lustrous, displaying the vertical striations typical to this species. Some of the crystals have an earthy brownish-black coating of ilvaite on one side. The only damage to this specimen is on the edges, and this is very minor.
no photo
ilv-4 ($ 42.00)
Lvl 5, Los Remedios Mine, Taxco, Guerrero, Mexico
ILVAITE specimen ilv-5
$ 105.00
Dims:2.0x1.5x1.4" (5.1x3.8x3.6 cm)
Wt: 2.9oz. (83g)
Lvl 5, Los Remedios Mine, Taxco, Guerrero, Mexico
A thick crust of brilliant, black, sparkling ilvaite crystals rests on a matrix of massive ilvaite in this specimen. The crystals exhibit the characteristic diamond-shaped cross section and vertical striations found in this species. For a black, opaque mineral, this is incredibly aesthetic. There is only minor damage on the edges of this specimen where it was pried from the host rock.
no photo
ilv-5 ($105.00)
Lvl 5, Los Remedios Mine, Taxco, Guerrero, Mexico
ILVAITE specimen ilv-6
$ 90.00
Dims: 3.18x2.58x1.22" (8.08x6.56x3.09cm)
Wt: 4.25oz (120.3g)
Dalnyegorsk, Russia
This specimen contains dozens of fine ilvaite crystals. They are black, opaque, and to my eye, they have more of a vitreous luster than the usual sub-metallic luster. Many of the crystals have a classic diamond shape, but many others are distorted, especially in that the crystals are curved. The faces generally show striations, and there is very little damage except around the edges of the specimen.
no photo
ilv-6 ($ 90.00)
Dalnyegorsk, Russia
ILVAITE specimen ilv-7
$ 45.00
Dims: 2.20x1.81x1.33" (5.58x4.58x3.37cm)
Wt: 3.90oz (110.4g)
Dalnegorsk, Russia
This is a specimen of nearly pure ilvaite. It has a shiny black color and an opaque submetallic luster, and the crystals individually have a distorted square cross section, and rough slanted terminations. An unusual aspect is that the crystals are nearly parallel at the base but then curve slightly outward towards the tips. Also, the crystals (while nearly parallel) have random orientations. There is a tiny amount of a dull white mineral present.
no photo
ilv-7 ($ 45.00)
Dalnegorsk, Russia
ILVAITE specimen ilv-8
$ 25.00
Dims: 2.62x1.24x0.79" (6.65x3.16x2.00cm)
Wt: 1.91oz (54.0g)
Dalnyegorsk, Russia
This specimen has five black ilvaite crystals on a white granular matrix. The ilvaite crystals are well formed, opaque, and have a vitreous luster, although the largest crystal is somewhat distorted in cross-section and is missing one side, due to a growth of tiny silvery-gray crystals (it just looks like a dull gray mineral to the unaided eye). I do not know what this mineral might be, although it has an appealing appearance under a high power loupe, having tiny flat circular crystals with a silky luster. The white matrix is also somewhat of an identification challenge. First of all, most of it is a loose, even crumbly assemblage of tiny transparent colorless crystals (which are too small for me to determine their form even with a loupe). Some of the crystals are long and prismatic, and these appear to have a hexagonal cross section, and while I don't see good terminations, there are some broken crystals that look like they may exhibit a conchoidal fracture. This leads me to believe that they are quartz (an easy default guess in any case), however the long crystals are very long and thin for quartz, and the granular matrix that easily comes off on your fingers feels too soft. Overall, the white matrix is translucent enough that I am certain no additional ilvaite crystals are buried inside.
no photo
ilv-8 ($ 25.00)
Dalnyegorsk, Russia


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