THE MINERAL AXINITE
- Chemistry: Ca2(Mn, Fe, Mg)Al2(BO3OH)(SiO3)4, Calcium Manganese Iron Magnesium Aluminum Borosilicate Hydroxide
- Class: Silicates
- Subclass: Cyclosilicates
- Uses: Only as a mineral specimen
Specimens
Axinite is actually a series name for a group of isostructural minerals. All have the same structure but are different in terms of chemistry. They are named for their respective enrichment in either iron, magnesium and manganese, except for the iron manganese intermediate tinzenite. They differ slightly in color and specific gravity and most collectors refer to any of them as simply axinite, that is why they are treated as a single mineral here. Below is a list of the members of the axinite series and some of their properties:
- Ferro-axinite, iron rich, lilac brown to black, SG=3.31
- Magnesio-axinite, magnesium rich, pale blue to gray, SG=3.18
- Manganaxinite, manganese rich, yellow-orange, SG=3.32
- Tinzenite, iron & manganese intermediate, yellow, SG=3.37
PHYSICAL CHARACTERISTICS:
- Color is commonly a lilac brown but also yellow, yellow-orange, gray, pale blue and even black.
- Luster is vitreous.
- Transparency crystals are transparent to translucent.
- Crystal System is triclinic; bar 1
- Crystal Habits include flattened wedge shaped crystals, often with a spatula or knife-like shaped edge. Also as granular and as parallel bladed aggregates.
- Cleavage is good in one direction.
- Fracture is conchoidal.
- Hardness is 6 - 7.5
- Specific Gravity is approximately 3.0 - 3.4 (slightly above average for transparent minerals)
- Streak is white.
- Other Characteristics: crystals are heavily striated on some faces and manganese rich axinites have been known to be fluorescent red.
- Associated Minerals are diopside, andradite, quartz, calcite, epidote, scheelite and prehnite.
- Notable Occurrences include Madera Co., California and Franklin, New Jersey, USA; Baja California, Mexico; Bahia, Brazil; Switzerland; Obira, Japan; Cornwall, England and France.
- Best Field Indicators are crystal habit, hardness, color and striations.
 Amethyst Galleries' Mineral Gallery MINERALS |
AXINITE specimen axi-2
$ 125.00
$ 125.00
Dims: 1.3" x 1.3" x 0.8"(3.3 x 3.3 x 2.0 cm)
Wt: 13.4 g
Saranpaul, Polar Urals, Siberia, Russia
This specimen consists of a cluster of several brown tabular blades of Axinite that are intergrown. The largest of these blades measures 0.8 x 0.7 x 0.1"(2.0 x 1.8 x 0.3 cm), and like its smaller relatives, has a vitreous luster and is transparent with good clarity along its edges that clouds towards its base. Apart from some tiny spots of conchoidal chipping along one edge, this largest crystal is also the most complete, missing almost no material. Other crystals in the cluster show perfect cleavage where parts of them are missing. There is no host rock, except for what appear to be a few bits of quartz on the specimen's underside.
axi-2 ($125.00)
Saranpaul, Polar Urals, Siberia, Russia
AXINITE specimen axi-3$ 200.00
Dims: 1.5" x 1.1" x 0.9"(3.8 x 2.8 x 1.8 cm)
Wt: 17.6 g
Saranpaul, Polar Urals, Siberia, Russia
Several brown, tabular bladed crystals of Axinite are intergrown on this specimen. All have a vitreous luster and are transparent with patches of cloudy inclusions and remarkable clarity. Their edges show bits of conchoidal chipping but are in good condition, and their faces are striated but clean. The largest of these blades is quite exposed and measures about 1 x 1 x 0.2"(2.5 x 2.5 x 0.5 cm). The smallest blades are no less than 0.3"(8 mm) long, and many of them are twinned. A few thin bits of what appear to be bladed calcite crystals are embedded in the underside of this cluster, but there is no other material. I really like this specimen because the crystals are large and their form is quite easy to determine.
axi-3 ($200.00)Saranpaul, Polar Urals, Siberia, Russia
AXINITE specimen axi-4
$ 95.00
$ 95.00
Dims: 3.0 x 1.7 x 0.9" (7.6 x 4.3 x 2.3 cm)
Wt: 1.9 oz. (54.0 g)
Bahia, Brazil
This cluster contains some of the largest Axinite crystals that I have ever seen. These crystals achieve lengths of up to 3" (7.5 cm) and are in excellent condition, showing almost no human-induced damage except for that which was done during the mining of the piece. The specimen is likely of the variety of Axinite known as Tinzenite, as it apppears to be a paler brown than Ferro-axinite, and has an almost lavender coloration along its edges. The blades have excellent triclinic form, with sharp edges and smooth faces that possess a bright, almost adamantine luster. Individually, the blades would likely be at least translucent at their thickest points, but in their clustered form, the thickest points are essentially opaque, even in sunlight. However, they do show translucence and even some cloudy transparence near and at their edges, respectively. There are tiny bits of some type of dull, tan-colored crust present in crevices between and on the crystals, but there is no host rock present.
axi-4 ($ 95.00)
Bahia, Brazil
AXINITE specimen axi-5
$ 50.00
$ 50.00
Dims: 1.5 x 1.0 x 0.7" (3.8 x 2.5 x 1.8 cm)
Wt: 23.6 g
Bahia, Brazil
This thumbnail specimn consists of a several intergrown Axinite crystals. I cannot be certain, but I believe that they are of a variety of Axinite known as Tinzenite, which contains both iron and manganese. The crystals do not exceed 1.0" (2.5 cm) in length or 0.6" (1.5 cm) in width, and are generally in good condition, though they do show some visble damage to their terminations. All have good triclinic prismatic form, with well-defined edges and clean faces that possess a bright pearly luster. All have a generally pale brown coloration, but their edges have a pale pink-to-lavender coloration. All are moderately to dimly translucent and show small patches of transparence. There is no host rock present on the piece.
axi-5 ($ 50.00)
Bahia, Brazil
AXINITE specimen axi-6
$ 80.00
$ 80.00
Dims: 2.2 x 1.6 x 0.7" (5.6 x 4.1 x 1.8 cm)
Wt: 1.4 oz (23.6 g)
Bahia, Brazil
At least 10 intergrown Axinite blades make up this large thumbnail specimen. The largest of these blades has dimensions of 2.2 x 0.8 x 0.4" (5.6 x 2.0 x 1.0 cm), and like the others, is in excellent condition- damage is minimal. Their triclinic form is excellent, with sharp edges and lightly striated but clean faces that possess a pearly-to-vitreous luster. All have a moderate brown coloration that fades to an almost pale lavender color at their edges. They are moderately transparent, but intense cloudiness spoils their clarity. There is no host rock present.
axi-6 ($ 80.00)
Bahia, Brazil
AXINITE specimen axi-7
$ 34.00
$ 34.00
Dims: 1.6 x 1.3 x 0.6" (4.1 x 3.3 x 1.5 cm)
Wt: 11.6 g
Dal'negorsk, Primorskiy Kray, Russia
This small thumbnail specimen consists of a cluster of Axinite blades that range in size from less than 0.1 x 0.1 x 0.1" (3 x 3 x 3 mm) to 0.8 x 0.4 x 0.2" (2.0 x 1.0 x 0.5 cm). All are in very good condition- damage is limited to a few small chips along the edges of the largest crystal, and the surfaces where the specimen was separated from its host rock. All have good triclinic form, with sharp edges and slightly curved but clean faces that possess a bright vitreous luster. They have a moderate brown coloration and are partly transparent with moderate to dim clarity due to the presence of many inclusions and internal fractures. There is no host rock present.
axi-7 ($ 34.00)
Dal'negorsk, Primorskiy Kray, Russia
AXINITE specimen axi-8
$ 25.00
$ 25.00
Dims: 1.0 x 0.5 x 0.3" (2.5 x 1.3 x 0.8 cm)
Wt: 11.2 g w/ specimen box
Daln'egorsk, Primorskiy Kray, Russia
This thumbnail specimen consists of a few partly intergrown Axinite blades. These blades do not exceed 0.1" (2.5 cm) in length, but are in excellent condition, showing almost no human-induced damage. Their triclinic form is very good, with sharp edges and well-defined but somewhat curved faces that possess a vitreous luster. All have a moderately deep brown coloration and are transparent and moderately clear, though some of thickest areas of intergrowth are merely translucent. The piece is hot-glued into a square plastic specimen box, and there is no host rock present.
axi-8 ($ 25.00)
Daln'egorsk, Primorskiy Kray, Russia
AXINITE specimen axi-9
$ 25.00
$ 25.00
Dims: 1.0 x 0.9 x 0.4" (2.5 x 2.3 x 1.0 cm)
Wt: 12.8 g w/ specimen box
Daln'egorsk, Primorskiy Kray, Russia
Several partly intergrown Axinite crystals make up this moderately sized thumbnail specimen. There is a substantial amount of damage to the specimen in the form of a blade or a cluster of blades that were broken of at their base. However, this portion of the piece looks merely like an extension of the base for the intact blades, which are in good condition, showing little damage. None of these exceeds 0.1" (2.5 cm) in length, and all have excellent triclinic bladed form, with sharp edges and slightly curved but clean faces that possess a bright vitreous luster. All have a moderate brown coloration and are transparent, though their clarity is hampered by intergrowth and what appear to be cloudy inclusions that are present in all of them.
axi-9 ($ 25.00)
Daln'egorsk, Primorskiy Kray, Russia
AXINITE specimen axi-10
$ 27.00
$ 27.00
Dims: 1.0 x 0.9 x 0.8" (2.5 x 2.3 x 2.0 cm)
Wt: 16.1 g w/ specimen box
Daln'egorsk, Primorskiy Kray, Russia
This thumbnail specimen consists of two intersecting clusters of Axinite blades. These blades are rather heavily intergrown with each other in their clusters, but are in good condition and appear to have good triclinic form. They are brown in color and have a vitreous luster, and are dimly transparent due to cloudy inclusions. There is no host rock present, and the piece is affixed inside a plastic specimen box with a removable putty.
axi-10 ($ 27.00)
Daln'egorsk, Primorskiy Kray, Russia