Having a crystalline structure visible only when magnified.
- ‘In these, the spicular aspect grades abruptly inward into dense cryptocrystalline silica, which forms the bulk of the specimen.’
- ‘Silica precipitated from aqueous solution at low temperatures gives cryptocrystalline varieties such as opal, jasper, chalcedony, agate, carnelian, onyx, flint, and chert.’
- ‘This cryptocrystalline silica can preserve with high fidelity delicate shell detail such as musculature.’
- ‘The textures of thunder eggs can vary from distinctly radiating fibrous textures to cryptocrystalline aggregates that preserve the structure of the original rhyolite.’
We take a look at several popular, though confusing, punctuation marks.