Homilite is a rare borosilicate mineral typically found in nepheline syenite pegmatites. Collectors look for its characteristic black to brownish-black prismatic crystals, which are often found in close association with other rare beryllium or boron-bearing minerals.
Is this homilite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch homilite with a known reference. Homilite sits at Mohs 5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: grayish.
- 3Read the lusterHold the specimen under a strong light. Luster: resinous to vitreous.
- 4Match the color rangeCompare against the expected color range: black, blackish brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular.
Often confused with
Homilite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Gadolinite-(Y) is the harder of the two (Mohs 6.5-7 vs. 5); streak differs, so Homilite leaves grayish, Gadolinite-(Y) leaves greenish gray; luster reads resinous to vitreous on Homilite and vitreous to greasy on Gadolinite-(Y).
How to tell apart: Streak differs, so Homilite leaves grayish, Datolite leaves white; luster reads resinous to vitreous on Homilite and vitreous, rarely subresinous on fracture surface on Datolite.
Often found alongside homilite
Minerals reported to co-occur with homilite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂Fe²⁺B₂Si₂O₁₀
- Mohs hardness
- 5
- Density
- 3.34-3.38 g/cm³
- Colors
- Streak
- Grayish
- Luster
- Resinous to vitreous
- Transparency
- Opaque, translucent only in thin fragments
- Crystal system
- Monoclinic
- Crystal habit
- Tabular
- Cleavage
- Indistinct
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In pegmatite
Where rockhounds find homilite
Classic worldwide localities
- Stokkø, Store-Arø, and Øvre-Arø Islands, in the Langesundsfjord, Norway
Field-hunting tip
Where it forms: In pegmatite. If you start seeing allanite, meliphanite, titanite in float, you are in the right ground. Typical habit: tabular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify homilite?+
Where is homilite found?+
What rocks look like homilite?+
What minerals are found with homilite?+
What kind of rock does homilite form in?+
What is homilite used for?+
Find homilite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
